iWater Flow iWater Flow has OF integrated for both Leaderboards and 17 achivements. And some of them are quite hard to achieve
gas tycoon 2 http://forums.toucharcade.com/showthread.php?t=31405 sky defender http://toucharcade.com/link/http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=335701997&mt=8
Runt the Rollbot is currently FREE and has OpenFeint achievements. Wheeler's Treasure $.99 also has OpenFeint achievements.
http://phobos.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=294739283&mt=8 Blackbeards assault A marble poppergame for 1.99
check out this app!! http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=334372984&mt=8 here are a lot of achievements .. )))
Runner's Challenge - with some fairly difficult (especially for those of us with an iPod) achievements! EDIT: Not compatible with iPod Touch
im surprised no one has set up a openfeint achievements website by now, similar to what has popped up with ps3 and xbox360. I'm sure lots of people would visit it.
gravity sling which was released just today has a lot of achievements in it. you can read about it here http://forums.toucharcade.com/showthread.php?threadid=32100
Cogitate (just released!) has OpenFeint leaderboards for each difficulty level and 21 achievements to unlock, some guaranteed to be very challenging!
I've just added the Achievements list to Uggles - Christmas Edition. We should be submitting later this week. http://forums.toucharcade.com/showthread.php?p=634627