I did a post on SloPro before, which lets you record slow motion footage on your iPhone 4S. Well the guys behind the app have just updated it to version 2.0, adding a slew of new features, the 1000fps feature probably being the most notable.
Obviously the iPhone 4S camera cannot achieve true 1000fps footage but what you can do is manipulate footage to make it look 1000fps. The app uses software which makes up for the frames between key frames, making it look like the footage is in super slow motion.
Other features include, Action Shots, renderless editing, edit while shooting, Fast Motion, 3 new slow effects, hardware acceleration, in-app sharing and the ability to see other videos people have shot with the app. Oh and not to forget, there is an iPad version now.