WordFoto is a photo app that will assemble a picture for you using both a source picture and any words you happen to throw in the text field. Basically, you put a picture and some words into the app, and the app's crazy algorithm spits out a picture assembled out of different variations of the two or three words you punched in. It's an interesting mix of images -- a little simple, honestly, since all of the pictures look about the same. But if you need a really interesting illustration or have a really great picture/word match, you can make some graphics that can be pretty striking.
The app itself is US$1.99 on the App Store right now, and it's got a ton of nice features, including custom styles for your photos in addition to the standard presets, the ability to crop and save your outputted photos, and of course you can share them out on email or Facebook as well.
The app's being updated as well, with new styles and features all the time. WordFoto is a fun way to make some interesting art. It's a little simple, but used in a subtle and careful way, it can make some really powerful graphics for you.