Programming Contests (with prizes)

Question

I've had a go at solving the Eternity puzzle (1,000,000 GBP prize) and Netflix Prize ($1,000,000) in the past. I didn't win either, but they motivated me to find out about a new area.

What other contests with prizes do you know about / have competed in yourself?

Answer 1

http://www.topcoder.com/

Answer 2

The Netflix Prize (for voting)

Answer 3

The Millenium Problems.

Answer 4

There is an eternity 2 project, although it has been out for a bit and the first solutions are being checked on Dec 31.

http://www.eternityii.com/