There are plenty of apps out that can take your environment and let you add your own style on top. But, using the iPad's built-in cameras, the Composite app lets you reinterpret that environment any way you like on the fly.
Developed by James Alliban, Composite is a really cool departure from your typical paint app. Inspired by the work of Robert Rauschenberg, whose "combine paintings" incorporated a variety of mediums and materials into collages, Alliban took the toolkit you'd expect from, say, Brushes and combined it with a video feed. From there, you can record your subject in real-time, toy with how it appears on your screen—all the way from the brush thickness to the video contrast—and make something really expressive. This is your new time waster. [iTunes, Vimeo via Creative Applications]