That's (among others) big screen buttons, simple playlist update from the contents of certain directories, and support of hardware buttons.

Included features:

• All basic functions (Play, pause, skip track, spooling, ...)
• Supports:
  
• MP2, MP3, Ogg Vorbis, and WAV (thanks to MAD, libovd, and Green Software...)
• GSPlayer plug-ins (e.g. for MIDI files)
• Playback of files on the net
• Shoutcast and IceCast streams
• PodCasts and online playlistst
• WinAmp and MediaPlayer playlists (M3U, PLS, ASX, WMP, read only)
• Native playlists (MPL, read and write)
• Equalizer (only MP3), sound effects
• Bookmarks (memorize positions in songs or audio books)
• Auto continue from position and/or start playback after restart
• Big screen buttons, easy to tap with your finger (at least in most Skins)
• Assignable hardware buttons (all buttons, almost every function)
• Screen saver (switch off display after some time or on button press) with optional button lock
• Fall asleep timer
• Alarm clock
• different wake times for each day of the week and a one time alert
• the player doesn't need to be running
• play a special file and/or continue current playlist
• Optional volume change on start, exit, and alarm clock
• Automatically pauses when doing a call (Phone Edition)
• Display of ID3 (V1.0-V2.3) and Ogg tag informations (track name, artist, album, year, track no., cover), as well as external cover images per track or path
• Add your favorite folders and playlist to Favorites. This enables you to choose them easily from a list in Open dialog or skip between them with the press of a button. You can even automatically include all subfolders. I.e., skip easily between all folders of \Storage\My music or wherever you put your audio files.
• Changer Mode: Automatically skip to the the next path or directory of your favorites when one is finished. Or shuffle between all directories.
• Simple file selection when adding new files
• Skins and Screens
• Full Skin support, you can decide for all elements if, where and how you want to show them! (sorry, own format only...)
• Multiple Screens (Easily switchable displays contained in one Skin)
• Extended screen switching support: Switch easily between a selection of Screens from multiple Skins
• Fullscreen support for Skins (no title and/or menu bar, e.g. for a car screen)
• "Always on top" option for small windows, thus allowing a small track display or similar on top of your navigation program
• You can turn off images to save memory and CPU
• User defined Playlist Font (or Skin default)
• File associations (start with double click on e.g. an MP3 file)
• User defined startup action (Changer Mode, recent playlist, update playlist, continue last track, ...), repeat and shuffle mode
• Write informations about the currently played track in a file or append it to a logfile
• And many more settings

For more info, read the manual or look at the screenshots.
There are some Skins and a manual how to create your own on this page.
A plug in for your Today screen is to be found here.

Update Description:
v3.31 b69 (RC8.1):
- Finger gestures in unassigned areas of the player (i.e. outside of buttons, sliders, playlist, ...): left/right=prev./next track, up/down=prev./next favorite.
- Backup/restore in settings now reachable on older systems than WM5.
- Writes more data to registry, should be compatible with last.fm for Window Mobile (you might need to enable writing track data in "Extra" settings).

v3.31 b68 (RC8): - Dragging a list works only horizontally or vertically, to avoid dragging it in the wrong directions (esp. horizontal movement when moving up or down).
- Bugfix with removing images of other screens (switching to a previously used screen of same skin works faster).

v3.31 b67:
- Bugfix at restoring setting backups.
- Lists can be "flicked" (up to 3 screens, stop by tapping).
- For Skins: Scroll bars can be omitted (set ScrollWidth resp. -Height to 0), new list propertes ItemHeight (minimum height for entries) and Lines (color for optional separator lines).
- Updated russian und japanese translations.

v3.31 b66:
- Setup program enables configuration backup (in "Menu") and default translations (setup_def.lng).
- Option to use tag infos in playlist (in "Open/Favorites" settings - better move to "Display"?).
- Option to write tag infos to registry (in "Extra" settings - feature existed in b65, but was missing in setup).

v3.31 b64 (interim versions) / b65:
- New default skin.
- Continue pause after call finally should work now (at least on most devices...).
- Make selected track in the playlist the upcoming one by tapping the "Next track:" info field.
- Preprarations for remote control from other apps (see beta thread in forum).
- Some bugs fixed (e.g. wrong setting entries (so the change wasn't found) or strange irregular crashes on some devices, when a status window should be shown).
- New simpyfied dialog for Favorites (only one directory for each music and audio books; you still can reach the old one with "extended", and it's automatically shown if your Favorites don't match the scheme).
- Lists can be moved by dragging the finger starting in the entries area (i.e. not scroll bars or somewhere around), when you move over or below, the list is scrolled by one entry every 150ms (but no fancy "flick" scrolling...).
- Default relative volume set to 80% like in most other players.
- Simplyfied wizard for those who don't like to use the Favorites.
- Updated playback system (MAD 0.15.1b).
- New button assignment: add new bookmark without dialog.
- "Minimize" button assignment reactivates player if the player's in background (of course must be assigned to an application button and "buttons in background" must be activated).
- Omit "user effects" when switching presets without dialog.
- Bugfixes in button handling.
- Bugfixes and improvements in skin handling (switch back to previous screen, wait_* not working correctly, ...).
- Bugfix in favorite switching (stops when more than 15 folders are empty or wrong type (i.e. audio book or not)).
- New/updated language packs.

v3.31 b63:
- New organization of settings.
- Continue after call can be configured in the settings.
- Autosave current position in regular intervals (default: every minute).
- Configurable separation of audio books when switching favorites The current MortPlayer beta - usually more up to date than the RC, but maybe a little less stable.

***** [Sep 20, 2007] by Scott using PPC 6700
I found that listening to music through my bluetooth stereo was very bad with every player I tried. Then I tried this player. Everything came through crisp and clear. It was like other players used to many resources and that caused them to skip.

***** [Sep 12, 2007] by Simon using Airis T620
Having read the reviews and run with GSPlayer for a while I finally gave up and tried Mortplayer. It is like a breath of fresh air, add my whole library is now possible, the sound is great and with all the skins in the default package I found one that works for me. Big buttons mean I can use it easily in the car. The sound quality is good, the program overall is awesome.

***** [Jul 12, 2007] by Clive using Pocket pc
Just absolutely amazing for a freeware program - its fantastic for any program come to that - so glad I found it.

**** [Jun 22, 2007] by Tom Craig using Dell x51
This is a very good player. I tried about 5 players and it striked the best balance between resource useage and functionality. Out of all of the players I tried, this was the only one that sometimes failed to read a valid MP3 file (VBR, cd-quality: > 200). A very good, but slightly flawed player.

***** [Jun 1, 2007] by Janus using N560
This is simply the best MP3 player for Pocket PCs; excellent menu structure and options, superb sound quality and VGA skins, which offer unlimited layouts. After having tried almost every MP3 player for Pocket PC there is on this site, I can honestly say, that this is THE ONE. Get it. Now. ^^

* [Apr 2, 2007] by Vince using O2 XDA IIi
In fairness I haven't tried this app but I think it is the ugliest thing I have ever seen. Ok I get the idea behind the BIG screen buttons, but if these are mapped to hardware buttons what is the point? PocketMusic commercial is worth every penny you pay. And heck the PocketMusic freeware has bigger and better laid out buttons than this thing.

***** [Nov 1, 2006] by Kelderek using Dell Axim x51v
Excellent player with loads of options, landscape mode and even VGA support. The default skins are not very good, but there are some excellent ones on the MortPlayer homepage.

***** [Dec 21, 2005] by Gary using HP 568
I think this is better than GSPlayer. The large skin button is great for my older PDA. Still lot's of great features to explore, which I don't mind. One feature needs to be added. When you select your MP3 files for play, there should be a feature to select all files from you folder. Other than that it is great.

***** [Oct 26, 2005] by Mort using MDA compact
Time for some remarks...
- Buttons in background: Of course you have to check the "also in background" option. However, some programs can override this. E.g., it would be a bit bad if you couldn't control your games while the player's in background...
- You can use network shares by entering the UNC path (that's \\server\share\path) in the edit field above the tree. The current beta also shows the history of the file explorer connections.
- Being at the new beta: Try it! It's already in RC state and available at the download area of www.sto-helit.de. I hope to be able to release it in a few weeks...
- As the playback code is 100% identical whith GSPlayer, there shouldn't be any quality differences...
- Why didn't anybody notice the favorites and Changer Mode? Do you all prefer loading and editing playlists? I just love to switch between directories with one click or shuffle all tracks... (Which was one of the reasons I wrote this thing...)
- A desktop version is not impossible (as GSPlayer shows), but a hell lot of work, esp. since I'd have to remove all that WM specific stuff (Buttons, alarm notifications, ...). Maybe I'll do it one day...

***** [Oct 21, 2005] by Thomas using HP 4700
VGA !!!! I tried the Winamp clone, but VGA was not supported, now I run this beautiful player on my desk, in CAR mode. A beauty!

***** [Aug 31, 2005] by princefan using Toshiba e800
Great player! It looks so beautiful in my 'True' VGA display. Many thanks to the developer for the raw VGA support. Yes, that's 640x480 without any pixel-doubling! I can't believe no one mentioned this aspect before.

*** [Aug 12, 2005] by Ben using Ipaq rx3715
Great player. Have one issue with key mapping options. Can't use the key mapping when the player is minimized. Seems as thought buttons are getting unmapped during background play. Didn't work on rx3715 or h2210. Any suggestions?

***** [Jul 13, 2005] by Preet Singh using HP Jornada 568
Excellent. Works great on my Pocket PC. Is there a similar program for a desktop PC (not counting Windows media player or real audio).

*** [May 27, 2005] by Mike Eckman using Dell Axim X50v
Decent player but the one thing it cant do is map to files on network shares. I have a whole Media PC on my network and I want to be able to store those location as my favorites, and this can't do that. It only allows you to play things locally stored on the Axim. :(

***** [May 23, 2005] by Ric de Jong using XDA 2
Excellent program, mainly because of the big button screen and the today plug in. Very good sound quality. Used GS player first, which has comparable sound quality but lacks big button feature and playlists. This program is far better than Mediaplayer. Especially sound quality and sound adjustments are far better. Try this!!

** [Apr 29, 2005] by Nelson Tee using O2 xdaII
I tried the old version and new version but it still interupting my device, such as keep on soft reset. Any better ideas.

***** [Apr 4, 2005] by A yousaf using XDA IIs
WOW. Best Player for PPC by far. Takes a little while to explore and setup the enormous amount of features. These guys have thought of everything...... & its FREE unbelievable. Ipod, eat your heart out!

***** [Mar 30, 2005] by denialnw10 using MDA/XDA II Mini
Clearly the best audio player for any pocket PC, don't bother download the rest all you need is this! It plays everything, has an alarm, sleeper, excellent playlist system if you have a 1Gb mem card like me you'll be sorted!

*** [Feb 21, 2005] by Jeff using Toshiba e335
It has much better file support than "Pocket Music", but the interface is clunky and slow. The playlist support is poor (should be able to sort by track number), and it has a lot of extra features I don't need (i.e. alarm clock, etc). Some of the skins available make it a little better to use.

***** [Feb 21, 2005] by Jason using Dell Axim X50v
Great program so far. Just DLed it but it is working great so far in the five minutes I have had it. Awesome setup and walkthrough!!!

***** [Feb 4, 2005] by richb using iPaq hx4700
I paid $20 for pocket music, then found this gem. I have tried most of the players out there, including trying to get skins for wmp for the 4700 and none of them come close to the power and capability of mortplayer. This program just works.

***** [Dec 31, 2004] by keat using O2 Mini
Forget about the other players, this one is the best. Do yourself a favour and install this, don't waste time on other players. Hopefully more skins will be available (the available ones are good, but more choices is always good).

***** [Sep 17, 2004] by Cheater using Asus a 620
Great program! I love it. The best player.

**** [May 12, 2004] by Chookfootman using ipaq 1930
A very nifty program! Big buttons good for when you're unable to use a stylus. Nice 'keep alive' function, screensaver with hardware button mapping is excellent. Only minor issue I've had is with playlists that have been deleted, it occasionally takes longer to load than normal.

***** [May 5, 2004] by Ayrk using Dell Axim x5
This is the perfect MP3 player, especially if you play them in your car. The designer made this program to not be a memory and processor hog and created large buttons for use in the car. I love it!