Creates huge rasterized images from any photo. It will convert a photo into a multi-page pdf file from which you can create a poster up to 20 metres in size.
http://homokaasu.org/rasterbator/
The online version only accepts files less than 1MB, but the free download will accept larger sized images.
Gallery of users assembled posters:
http://homokaasu.org/rasterbator/gallery.gas