A gathering of puzzles including many old chestnuts but also perhaps one or two you haven't met before.
posted by Wolfdog on Dec 16, 2009 - 29 comments

"Project Euler is a series of challenging mathematical/computer programming problems that will require more than just mathematical insights to solve. Although mathematics will help you arrive at elegant and efficient methods, the use of a computer and programming skills will be required to solve most problems."

Started in 2001 as a sub-section of Maths Challenge, it has since grown large enough to become its own entity. It now boasts over 200 problems, many of them insanely difficult. [more inside]
posted by mystyk on Oct 13, 2008 - 31 comments

If you could use a great big free handbook of discrete math and algorithms, Jörg Arndt's fxtbook wants to be your friend. Plain text table of contents to whet your appetite.
posted by Wolfdog on Mar 5, 2008 - 11 comments

Project Euler is a running contest of programming challenges to hone your algorithm skills. "Each problem is designed according to a 'one-minute rule', which means that although it may take several hours to design a successful algorithm with more difficult problems, an efficient implementation will allow a solution to be obtained on a modestly powered computer in less than one minute."
posted by Wolfdog on Aug 20, 2005 - 11 comments

Algorithmic Obscenity [maybe nsfw?] Who knew math could be this much fun? [via BoingBoing]
posted by srboisvert on Nov 15, 2003 - 5 comments