A tool which matches your handwriting to a latex symbol
A movie explanation of the Snake Lemma, and more math in movies
Soxaholix is a daily must read. Where else are you going to get wacky Red Sox commenatry and obscure literary references in a neat, comic strip package?

The Brushback is the best source of satire I've ever seen. The Onion might draw on a wider base for its satire, but The Brushback is far more biting and hilarious.

Speaking of The Onion, I love the fake editorial cartoonist Kelly aka Ward Sutton Another cartoon I love is The Pain