Puzzle sites
http://puzzle.dse.nl/index_us.html

http://www.chlond.demon.co.uk/academic/puzzles.html

http://thinks.com/webguide/mathpuzzles.htm

http://www.eduplace.com/math/brain/

http://www.brainbashers.com/

http://barryispuzzled.com/

http://www.braingle.com/