Puzzles
- erichs puzzle palace
- BrainBashers: brain teasers, games and illusions ...
- tricky and clever puzzles, baffling and perplexing illusions etc.
- user submitted and ranked brain teasers and logic problems
- BrainHelper.org - a website dedicated to the human brain
- Logic-Puzzles.org
- pzzls - puzzles, riddles and brain teasers
- monkeying around - dot-to-dot books
- puzzles of Leonid Mochalov
- cyber teaser
- higher mathematics
- math as a science, illusions ...
- another archive of mathematical puzzles
- Puzzle Games
- Bruno's chess problem of the day
- Free online jigsaw puzzles
- optical illusions, hidden images, impossible objects, upside downs and wordplay
- optical illusions, 3D images and other mind-teasing oddities