Optical Illusions Etc...
Entertainment, Games, Puzzles, Brain Teasers, Optical Illusions - Optical Illusions Etc. Contains many optical illusions in blog format.
https://illusionsetc.blogspot.com/
Optical Illusions at Mindfake.com
Entertainment, Games, Puzzles, Brain Teasers, Optical Illusions - Mindfake.com. Site contains a collection of optical illusions, online games, and other fun things.
https://www.mindfake.com/
Conceptis logic puzzles - Have fun, get smart!
Nonstop fun with the world's best logic puzzles: Sudoku and Sudoku variants, Pic-a-Pix, Link-a-Pix and other logic puzzles updated weekly. Play online and print on paper.
https://www.conceptispuzzles.com/index.aspx
griddlers.com: The Best Search Links on the Net
Entertainment, Games, Puzzles, Brain Teasers, Nonograms - Elite Japan Crossword. Downloadable software for solving paint by numbers puzzles in many formats, including plain black and white bitmap files.
http://www.griddlers.com/
Between Waters
Entertainment, Games, Puzzles, Brain Teasers, Cryptograms - Between Waters. Daily problems and solutions available with or without interactive browser-based solver.
http://www.betweenwaters.com/