Wow wow wow! From Wolfram Research, brainchild of Stephen Wolfram, author of the amazing Mathematica, and author of the new book A New Kind of Science (also see Wolfram Science.com about the book), which is supposed to change the world when it comes out: Eric Weisstein's World of Mathematics. It's an awesome math reference site (check out their entry for the derivative). I found it from the Paul Graham article I just blogged, where Graham referenced Euler's Formula, that awesome formula which relates e, pi, i, 1, and 0.
I've been looking forward to Wolfram's book for awhile, and I should have been able to point to my previous blog entry about him, but I didn't blog it because I was too tired. I still have links sitting on my desktop about him from months ago so that I could blog them... maybe later 
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