Im currently writing one in Qt at the moment. Im planing on having the following features built in:

1) Alarm/snooze function
2) Play alarm sound
3) Play a chosen MP3
4) Play a chose internet radio station
5) Play a video file (havent confirmed yet)
6) auto power off / screen lock etc
7) themable with initial iphone look
8) support for both portrait and landscape
9) command line support
10) full screen / normal screen support

Any suggestions welcomed!