Travis Goodspeed makes lots of hardware gadgets [1], he also gave a really cool talk about "Writing a Thumbdrive from Scratch" (for antiforensics) [2] at the 29th Chaos Communication Congress [29c3].
[2] in above was a very impressive talk. Mr. Goodspeed appears quite comfortable on stage, although I think his 'antiforensics' was somewhat less interesting than the notion of exploiting the fact that so many USB drivers exist and that flashing device firmware isn't super difficult. Probably a ton of exploits are possible by building device firmwares that behave unexpectedly and have not so robust drivers in the OS. Dropping a stack of malicious thumbdrives with not just evil.exe on them, but actual evil firmware is an interesting concept.
[1] http://goodfet.sourceforge.net/
[2] http://www.youtube.com/watch?v=D8Im0_KUEf8