TCPMP - Famed media player which will even play video. by far the best that's out there. I've included some codecs which were hard to come by.
Thumbboard - application to turn the full screen into a virtual keyboard.
iPhoneimitation - An iPhone imitation - what else?
Pocket Tunes - Best audio player for Palm.
Scrabble - Practically the only game I play on Palm
Softick Audio Gateway - Stream audio from your media players through bluetooth to your bluetooth headset.
Wifile - Access your files wirelessly
Documents to Go - Document editing and viewing. Best out there.
Resco Explorer - An explorer for Palm with the most functionality you will find.
Agendus Mail - My favorite mail app. Nicest GUI of them all.
SnapperMail - Others' favorite mail, has the most options.