Are fingerprint readers old hat for you now? Try the Jiris JCP1000 from Jiristech, which uses your iris as authentication. Program in your eye—either one is fine, unless you're a pirate—and the Jiris will pick up your eye signature in a second. The included software also encrypts and decrypts your files.
This works fine as a security device until you think of all the times in the movies where someone's eye gets cut out in order to authenticate on a computer/security system.