I did try one of the games once and was underwhelmed. It might have a calendar and an alarm, but I haven't used that either.
So now comes something that might almost be useful. iRocker software for the iPod includes the following:
200 essential chords (absolutely no, non-essential chords here!)
Tuner - well, it just plays an E it seems...
Metronome - 10 (count 'em! - 10) different speeds
Five (count 'em) chord progressions to jam along to.
All for $29.95.
Is it worth it? Hard to tell. Certainly not worth buying an iPod just for that. On the other hand, if you already have one, the chord library might come in usefull.