You know those cool photo mosaic thingies, where you get one big picture, but it's actually made up of hundreds of little pictures? It's sort of the 2000's equivalent of the 1990s Magic Eye posters in the mall.
I was Netscapin' this morning, and came across this bookmark, which goes to an Image Mosaic Making Thing, which lets you upload your own pictures and turn them into image mosaic thingies, like mine right there. The higher the contrast in the original image, the better the mosaic result. Also, I converted this from 1.4MB file to a 32K .jpg (you're welcome, dial-up users) but if you simply must burn my bandwidth and see the full-sized file, you may click it to embiggen.
I recall reading somewhere that there's a tool you can use to build these using your own images, but if you're just interested in getting one made quickly and easily, this is a dangerously fun way to avoid being productive.