Obfuscated awesomeness in C

Recently I've been bumping into obfuscated tiny C codes that does magic. Codes that are couple of lines in length but require pages of explanation on how it works.

There are lots of these in The International Obfuscated C Code Contest page, but here are some of the cool ones I've found in other places. (I'll update this list as I bump into more)

Yahoo! Logo ASCII Animation in six lines of C
20fps, antialiased ASCII art animation of the Yahoo! logo in six lines of C.

Donut animation
Donut animation with, well, donut shaped code. More impressive version here.

Spelt Number to Decimal
Spelt number (like, one, four, etc) in four lines of C

Brainfuck interpreter in 2 lines of C
For those who didnt know Brainfuck is a programming language.