Hero Academy is awesome.
It's a turn based strategy game on square tiles with (currently) 4 factions, it's also coming to steam late this year and each faction has (I think) 5 heroes with unique abilities and each faction has a unique theme.
It's pretty awesome.
Jetpack Joyride
It's a free (completely free, not free-to-play) game from Brisbane's Half-Brick, the guys behind Fruit Ninja. It's awesome fun and amazingly addictive.
It's awesome.
Between these two games I don't need any other iPhone games. I do have solitaire, Draw something, and Checkers, but they're pretty boring and standard.