- Bookshelf LT (free ebook reader, capability of downloading / displaying several formats - this is what my iPhone mostly gets used for!)
- Google Earth, although ... I'm not sure how really useful it is, since it pretty well just replicates that Maps app
- ICanHasCheezburger. Flip through pix from ICHC, FailBlog, EngrishFunny, GraphJam, and several other sites.
- Space Deadbeef. Fun side-scroll shooter
- AirMaster. 3D flight shooter
- DogWhistler. Annoy friends and co-workers with high frequency sounds. Oddly, dogs and cats don't seem to care about it however.
- Flashlight. High-brightness white screen, for use in dark rooms as a flashlight. You can set it for strobing and other colors, too.
- Thumper. Whack-a-Mole, with the ability to use custom photographs ... including your boss, ex-wife, etc.
- SuicideGirls. Flip the phone upside down, watch their clothes come off!
- Minesweeper. Uhh ... just what it sounds like.
- iConvert. The only paid application I have, and it was cheap. Unit conversion that I use at work a lot. you can convert very nearly ANY kind of unit to any other kind of unit. Includes even some archaic measurements - rods, furlongs, stone - and several less commonly used ones, or ones found generally only in industry.