Fingerprint scanners aren't exactly new, but they're still sort of a luxury in that no one I know uses one. Finding one that works on a Mac is slightly harder still. Upek's Eiko Digital Privacy Manager does work with Macs, bless its heart, hence my writing about it. That it's only $40 is also groovy.
You know the deal: plug it into a USB port, configure the software, and access to folders or files is restricted. Presumably it's for people have sensitive material on their PCs and Macs; I have about 50 gigs of music you're only likely to hear in the more “festive” neighborhoods of New York, so I really have nothing of value.