From Toysoft Development:
Have you ever wanted to replace a specific application's alarm sound, system MIDI Alert sounds, Hotsync or Treo 600/650 Radio on and off sounds with wave/mp3/ogg/wma/aac sound file? Ever wanted to wake up and hear your favorite song in the morning? Now you can with KoolSounds. KoolSounds allows you to associate any uncompressed wave or mp3/ogg/wma/aac (requires PocketTunes or AeroPlayer) file to any application. When the application's alarm is triggered, KoolSounds will play the sound file from the external card and then let the application sound the alarm. KoolSounds works with most applications with alarms.
Now you can have more fun with your Palm and you will never be bored hearing the same old system sound again.