If you've got the schematics for the next big gadget saved on your thumb drive, one of Rehoboth Tech's Irikon flash memory sticks might be as secure as it gets. Touted as the world's first iris-scanning USB drive, the Irikon can remember up to 20 different eyes as authorized users and comes in sizes of 1GB to 4GB.
Not much at all, but secure drives tend to run smaller. The Rehoboth site is a little vague as to how the scan works, but with a rechargeable battery built in, as well as a 6cm scan range, we're guessing you give the drive a look at your eyes before you plug it into the port. It would be horribly awkward to always have to lean down for the scan—especially if the drive was plugged into a desktop.
Right now, it doesn't look like Rehoboth Tech's drive is available. And since Rehoboth is headquartered in South Korea, we might have to wait a bit. Until then, there's always fingerprint-reading USB drives, though iris scans are supposed to be faster in general. The Irikon recognizes eyes as valid or unauthorized in under two seconds.