I'll say this: Sticky is an original one. It's sort of a platforming game, though there are no real platforms involved. You play as a little orange blob named Sticky, tasked with saving the world from invading black blobs that slowly move from one side of your iPhone's screen to the other. Sticky can defeat these enemy blobs by bouncing on their heads, so it's your job as a player to catapult him back and forth around the little levels in order to hit the bad guys exactly right.
The game is fun, cute and intuitive, and while it's pretty easy to beat the individual stages (at least until power-ups and more obstacles get added into the mix), each stage also rates you out of three stars, so you need to race against time to try and grab a perfect rating as well. Hardcore gamers will want to clear out all of the levels, while younger (or just more casual gamers) can bounce Sticky around and still enjoy playing.
Full Game Center (and Crystal -- Chillingo is publishing) integration extends the experience, and the fact that it's only US$0.99 means it's probably worth a try if you're interested. It probably won't pull me away from Tiny Wings completely, but it's another fun casual experience.