Used to be that to create a photo mosaic, you needed high-end, expensive software to do it. But with the proliferation of on-line photo processing web sites, this is no longer the case. There is now a site that allows you to create your own free photo mosaic with no special software required on your computer.

Go to http://www.picartia.com/ and you can create your own photo mosaic. You get to choose the end picture that will be created as well as all of the photos that comprise the mosaic pieces. The only down-side to this service is that it only works with JPG images. But I suspect that'll change at some point soon.