The Autopen is a wicked vintage gadget that lets you store your signature as a series of mechanical cues for a multifariously branched mechanical armature. Gizmodo has a killer post on it, with old pop-sci articles on the forthcoming age of the autopen. Lots of online info revolves around how to tell if your collectable souvenir signature came off an autopen or an original signature.
The most useful one, though, is the Autopen, made by International Autopen Co. of Sterling, VA., a popular device that is apparently still in use (the Republic National Committee bought one just this year). The Autopen is loaded with special metal 'matrix' -- basically a traced pattern of the signature -- that can be used again and again, even if the signer isn't there. Even better, owners of Autopens can purchase signature matrices through the mail from third parties, duplicating any autograph at will. Current models of the Autopen weigh around 100lbs, run off regular power, and can use real pens and pencils (although they work better with Sharpies, due to the fixed width of the pen looking less off when done with marker).Link