PuzzleManiak - Best iPhone Games
Puzzle Maniak is a collection of 20 logical puzzle games. Most are of Japanese origin. Each puzzle is generated on-the-fly so you have an infinite amount of puzzles.
My favorites are LightUp, Loopy, Bridges, Rectangles. and Net. You can play tons of all these games for free on your Mac/PC.
ArcadeManiak - Best iPhone Games
Arcademaniak try demo (first levels only) is very similiar to PuzzleManiak but is more of an achievement based game. Try to beat each level as quickly as possible. 6 levels for each of the nine games. Times are posted on arcademaniak.com to compare with others.