I've already fallen in love with Noir -- a universal app for giving your photos a cinematic look by converting the image to black and white or a tinted monochrome and adding dramatic lighting. Similar to some of the tilt-shift apps, you can focus the shape of the lighting to really bring out a particular point on the photo and fade everything else into the background. The interface is simple, but powerful, and it does an excellent job of encouraging experimentation. You can pick up Noir for $2.99 on the App Store.
The second app is Movie Looks for the iPhone. Movie Looks sets out to give your movies the same kind of cinematic color treatment that Red Giant Software has specialized in with its professional tools. Rather than focusing on a lot of customizability, Movie Looks is preset driven, and there are three additional $0.99 preset packs that you can purchase in-app. There does seem to be some criticism on the App Store to be aware of thanks to (appropriately) long render times, and also because users (who didn't read the description) don't like having to use in-app purchases to unlock the entire looks library. Like Noir, Movie Looks is also $2.99 on the App Store.
If you're fast, Plastic Bullet
-- normally $1.99 -- is free today in celebration of Noir and Movie Looks being released; it's a must-have for your library.