Mine (old palm tungsten t3) - notebook, calendar, pic album, complete oncology nursing resource in my hand at work, newspaper, contact list (names addresses emails & more) games when bored, memo voice recorder, alarm memo - are all the apps I regularly use.
The killer reason for me using one over the old filofux jobbies is that each night it goes on the cradle and boffo - everything is copied to the mac. if I lost it or had it nicked everything is on the mac ready to use/download to a new one.
gps bluetooth
tom tom western/eastern europe
nearly 1000 ebooks
calander
diary
address book
e mail software
loads of games
movie playing software
several movies
office software