This guy at MIT has created a combination X/OR and AND gate -- using water. This guy rules.

And dig this:

In fact, Fluidics is a very important field of study that is widely used in aerospace or mission-critical applications, where eletcronic control devices don't offer the reliability or cannot support the environment. Also, military technologies use Fluidics in order to prevent malfunction in a nuclear war, when eletric devices cease to work.

(This item comes courtesy the folks at Slashdot, and a great discussion is ongoing. "Should have great floating point performance." Geek humor.)