Semi Secret Software (the same folks behind the amazing Canabalt game for the iPhone) has released its second game for the iOS platform, Gravity Hook HD. I actually heard about this one way back in March, and it was made even before Canabalt was. But this iPhone and iPad release has been updated for HD, and it's kind of fun. To play, you tap on various hook points in order to send your little guy skyward; you do this while fighting gravity and trying to keep from falling off the bottom of the screen. I can't say it's as fun or as simple as Canabalt, but it is colorful and addictive for sure.
You don't believe me? Go play the free Flash version on the website. If it hooks you (get it? Hooks?), you can pick up the universal app for iPhone or iPad for US $2.99.