Chalkboard + Beer Tap == Tap Boards - Boing Boing Gadgets
via Boingboing
Tap Boards are brilliant little chalkboards inside wooden taphandles, making it simple to mark what beneficent liquid will flow from the spout below. They were made with the homebrewer (and pro-am homedrinker) in mind, designed as they were by the fellow who runs Kegerators.com*, but they'd be great for any busy bar that changes its selection often.
There's a whole site for the Tapboards, but if you want to actually just buy them, they're currently at an introductory price of $22 a pop plus shipping.