Via BoingBoing I just stumbled about the Stamps.com photo service which allows you to create your own custom stamps for snail mail. It's for US stamps only so it's of no use to me.
But if you're in the US and don't have a Christmas present for your geek friend, yet1) why don't you give him a set of DokuWiki stamps?
You can use this image to build one and if you do please send me a postcard
hey it's only 10 months left!