olloclip for iPhone
You probably aready know how cool it is, but if you haven't its a great addition to the iPhone 4(s). The only thing I wish could be changed is to make the Fish Eye removable since I don't use that as much. Still its worth the $69 if the iPhone is your primary camera. The lowest I've seen this go for is $50 a while back, so it might be worthwhile to shop around.