Shapeways is a 3D printing website that can make pretty much anything you can design. They have just expanded their repertoire into stamps with Stampmaker. Stampmaker takes any type of grayscale image and turns it into a bump map. the brightest parts become the raised bits of the stamp, the darkest parts are the base. The finished stamp is 9cm × 13 cm and costs US$25.
With the Stampmaker you can turn your digital images to stamps and stamp everywhere and anywhere. Turn your drawings, your photos or any vector graphic into a stamp.