iMobsters - Also addicted to this 24/7 RPG game!
iFooty Plus - follow your team, it messages you goal updates from all your teams games using the BBC commentary and itonly costs £1.19, bargain!
AroundMe - Great for finding restaurants, shops etc.
FlickCricket - pretty self-explanatory!
PocketDyno - Not tried it yet but apparently it times your cars 0-60 etc, be interested to see how good it is!