Good job, this looks really cool. It's good how you've gotten so close to the original image without using too many tiles..

You might enjoy this: http://www.FrancisShanahan.com/collage/bezos/bezos_b.aspx

It's the same idea but done with Amazon products. The extra twist is that each collage is interactive, you click a tile and it loads that product!

This is pretty cool (Sorry for this late comment! :) I was wondering if want to show your code ? That's really interesting.