Isn't it supercool? This week I started an assignment on the Mac at work that got me all inspired to look for things I could do on my PC at home. I suppose you could try it all from scratch, but you should know there are easy programs out there to play with.

I used the share ware version of Mosaic Maker. You can use it for free for 30 days. The program takes care of the rendering of the pictures, while you can decide on shapes and other features.
You need a lot of pictures for the most life-like result, but it's fun to try out all the options.