You will need 56 monkey legs, a gallon of mustard, and the worlds largest ball of yarn. Kidding aside, you can use this: http://gamesalad.com/
seanunited97, you'll need some patience, a ton of willpower and of course Mac with Mac OS X Lion and free-to-download Xcode.
If you're serious about this, you'll have to have knowledge of Objective-C, use XCode on the Mac and pay Apple $99 to register yourself as a iPhone developer and publish your app to the App Store.