If you’ve ever wondered how those mosaic posters you see for sale are created, it’s a good chance they used this program. A free download (http://homepage.mac.com/knarf/MacOSaiX/) it has the performance and functionality of something you’d expect to pay hundreds for. You can choose your own source (Google images, your own iPhoto library, a QuickTime movie, etc), specify tile shape, frequency, match proximity, dimensions, and several other parameters.

The new version just released, v2.1, fixes several bugs and adds much needed support for multicore systems. A 20k tile mosaic takes under an half an hour using an 8-core Mac Pro at 700% CPU with 2GB of RAM used. Expect increased times with slower computers and less RAM.