Ed Pegg's Math puzzles
Stone's Java applets (Puzzles, CAs, etc.)
Robert Abbott's Logic mazes
Martin Chlond's Integer Programming in Recreational Mathematics
William Paulsen's Prime maze
Hirofumi Fujiwara's Java and Puzzle World
Andrea Gilbert's Click mazes
Jaap's Puzzle Page (Info on Rubik-like puzzles)
Chess mazes
Just skidding