I'm a big fan of visualization. Seeing my del.icio.us feed for the day, I saw this RegEx visualizer built by Oliver Steele. It's not meant to be a regex workbench or validator (It does not recognize certain character ranges like [1-5] or qualifiers like {1,3}). Still, its educational and just reading "non deterministic finite-state automaton" brings back memories of Chomsky and grammars and hanging on to dear life to get a 3.0 :-)
I still have my book "Introduction to Automata Theory, Languages and Computation." As a wise professor used to say to us in class, "Reading (esp. difficult text) stretches the mind". I keep it mostly to intimidate and appear smarter ;-)