These are five iPhone games that I really like and/or spent hours playing.
Words with Friends. Variant of Scrabble. Play 1 on 1 against friends or random opponents. Paying not to see ads is totally worth it.
Spider: Secret of Bryce Manor. Move spider with your finger. Spin webs. Eat bugs. Worth buying for the fantastic intuitive controls alone.
Electric Box. Make 50 Rube Goldberg Machines to get electricity from A to B. Play for free on the web, or take it with you on the iPhone.
Azkend. Match 3 puzzle game with fun power-ups, great artwork, sound effects, and interface. Get it for your desktop or iPhone.
Drop7. Simple falling number puzzle game. Match the numbers on the circles to the number of circles in the row or column to clear.
There. 5 games at 140 characters or less.