This script was created by me at Mashed08 as it was something cool I could build that used the Flickr API. Most other montage tools take around 15 minutes to work as they actually get each Flickr image, detect the colours, and then build the montage according to the colours available. My script, however, spits out all the images it finds and then renders transparent PNGs in the correct colour (with some opacity) over the top to colour correct them. A bit hacky but it's very fast!
To use it, just type a Flickr tag below (try typing "iPhone" or "bendodson" if you're stuck for ideas). A random image with that tag will be found and created from other images with the same tag. You can click on the pixels of the montage to view the images that have built it.