The Exploratorium (here in SF) is running an old Charles and Ray Eames exhibit called Mathematica:
A World of Numbers and Beyond through May 2002. The purpose is make abstract mathematical concepts more real through demonstrations including, "light bulbs and plastic balls that express complex concepts in math." Sounds fun, and if you've ever seen the Eames' film Powers of Ten, you know they can take the word "obscure" out of mathematical concepts.