Digitally signed ID cards
FaceCerts is a MS Research project that aims to improve the security features of ID cards like driver licenses.
The problem is making sure that the picture corresponds to the ID. The solution they came up with is to scan the picture, normalize it and sign it cryptographically. The signature is then printed on the ID, in form of a barcode, and proves that the picture matches the information on the card and the card was issued by the signing party.
The advantage of this technique is that it doesn't raise the cost of making IDs too much (plain paper is still enough). The article doesn't mention the cost of the device that does the verification though. I'm also not sold on the usefulness against terrorists, because I don't know that they use tampered IDs.
But it is still a pretty cool idea in general, to strengthen a real-life document by binding it with digital attributes.
Maybe this could be combined with PARC Research's DataGlyphs technique, that includes scannable digital information within images.