My iPhone is fairly new, so I have still a lot of apps that I'm trying out. Only the first three pages are the apps that I will keep for sure.
1) all default iPhone apps + Remote
2)Wi-Fi Finder, AroundMe, eBay, Shazam, Facebook, BeejiveIM, Tweetie, iNXES, Measures, iTranslate, Evernote, 1337pwn, 1Password, BBC iPlayer (link)
3) Dice, Rolando, Topple, Topple 2, Blocked, TanZen, Dizzy Bee, Dizzy Bee 2, Zen Bound, Ancient Frog, Sway, Touchgrine, Fieldrunners, Tap Tap, Galcon, Skybound (all full versions)
4) PocketGamer, Wild West Guns Lite, Defend! Lite, Poker Quest, Tiki Lite, Zentomino LE, Radio Flare Lite, touchPhysics Lite, Labyrinth LE, Toy Bot Free, Mouse About Lite, Undead, Movie Lite, monstertyper, Hexile-FREE, TicATac Lite (lite versions that I'm trying out)
5) VNC, Wikipanion, Xbox Guide, Darkroom, iPetPhoto, PhotoSwap, Pixelpipe, ShoZu, BinauralBeat
6) a bunch of free iVerse comics that I'm trying.