Keyring for all my retail discount membership cards... would be better if you could create categories; I'd love to sort my airline and hotel cards into their own folder etc...
K-9 Mail of course, way better than native gmail app.
Google News, good way to waste time with the headlines
History Eraser. One touch cleaning out all your call logs, message logs, browser...
Scanner Radio - listen to police/emergency radio around the country... good time waster.
Urban Spoon, of course.
WiFi Finder - lets you see mapped free access sites anywhere, and help you locate signal and connect.
Gas Buddy, again of course.
And because I'm a Comcast user - Xfinity mobile. Some reviews are pretty poor, but a lot of bugs have been fixed. Can see what's on tv, set my dvr, change channels, check my home phone to see if I missed calls, have voicemails, and soon they plan on adding the streampix streaming movie/tv shows for subscribers.