Tapestry a webcrawling collage-maker. Starting from a webpage, it will follow links and paste the images into a composite. For each collage, it keeps a fair-sized catalog of webpages to look at, and anyone can add to that catalog, "nudging" it in different directions.
I started ones for MIT, the SCA, FBC, and Flickr photos. There's also a tool for making your own (size-limited for now).
The process of making it web-accessible left it buggy, but for a while it looked like my shared host had made it totally impossible, so I'll take what I can get.