Lambda-calculus demonstrated as an alligator-and-eggs game. Neat!
Blog by "Old Bag": daily index card scans showing interesting intersections and correlations.
I especially recommend "Waveform" (second page I think)
There's a lot here - this is a much denser guide than the average internet Excel guide. Me happy.
Fantastic demo of finite state automata and regular expressions. Inoperative as of 2011-04-08.
"the text of the book Inner Algebra"