A Photographic mosaic is a picture (usually a photograph) that has been divided into (usually equal sized) rectangular sections, each of which is replaced with another photograph of appropriate average color.

For my project I use a program called metapixel. Metapixel is GPLd command line program that runs on linux (and other unixes).

For images, I am using Yahoos image search API. I pull back 1 image and that becomes the reference image. I then pull down the next 50 images and they are combined into a mosaic of the first image.

The more images you use the better the mosaic looks. Since I am running on a shared server, I only pull down 50 thumbnailed images from yahoo.

If your a windows kid, you can get similiar software to run on windows at photoutility.com.