Math Puzzles and Challenges

A friend of mine recommended the site mathschallenge.net for those interested in mathematical puzzles and challenges, including programming problems. I haven't had time to try it, but it looks good, with several problems of different difficulties posted each month. Perhaps something for Abiola, on his site Foreign Dispatches such problems sometimes appear, or for Jan Nordegren posting almost daily on his math-problems blog think again.

(Political sidenote: thinking again over Jan's Ronald Reagan quote: "Abortion is advocated only by persons who have themselves been born." - couldn't it just as easy be rewritten into an argument against death penalty? According to reasoning in the book Freakonomics, crime and free abortion are statistically and economically related (negatively!). I got said book recommended from the same person who recommended the math-site, that's how it all - however barely related - ended up in this post.)