Last night, inspired by a comment on HN about creating images with randomised neural nets by mapping inputs (x,y) to outputs (r,g,b), I spent some time trying to train a small neural net to approximate Lenna, the famous image processing test input. The outputs are quite interesting to look at, but don't approximate Lenna very well. But I don't know anything about machine learning, so I think you could do much better than I managed.
