I've been playing with Image::Magick lately. I started with photomosaics, which require a lot of CPU power and time. Although I had some success at creating them, I problem need to use larger source JPGs for a better mosaic.
The next thing I did was create a montage of graphics pulled from Rich Site Summary files. Check out these at Taskboy. Unfortunately, I don't have a general solution for creating these yet. To make them interesting, they should follow the links mentioned in each RSS item. Oh well. It's a fun toy anyway.