Websites for logic, riddles, and puzzles:

http://www.brainbashers.com/logic.asp

http://school.discoveryeducation.com/brainboosters/

http://www.rinkworks.com/brainfood/

http://www.mysterymaster.com/puzzles/index.php

http://www.puzzles.com/PuzzlePlayground/WelcomeToPuzzlePlayground.htm

http://www.sheppardsoftware.com/braingames/braingames.htm