Vast assortment of puzzles broken down into American, educational, cryptic, and themed categories. Also, provides links to other puzzle sites.
http://www.crossword-puzzles.co.uk/
Logic-intensive puzzles, with the types ranging from geometry, math, weight, moves and miscellaneous.
http://www.freepuzzles.com/
Games designed to be different from most other games. The site is against war and/or elimination games, because it prefers more friendly games.
http://www.gamepuzzles.com/
For teachers, parents and students who seek engaging mathematics-based puzzles and games.
http://www.cut-the-knot.org/
Devoted entirely to mathematical puzzles, with new updates every day.
http://www.mathpuzzle.com/
Choice of puzzles and games for all ages. Crosswords, word searches, brain teasers, number puzzles, word play, jigsaws and other online games.
http://www.puzzlechoice.com/
Challenges your brain with free puzzles, Shockwave and Flash games, crosswords, logic games, IQ tests, trivia games and contests for prizes.
http://www.puzzledepot.com/
Large puzzle site. There are puzzles to play and/or buy; links to other puzzle sites; and a puzzle project link.
http://www.puzzles.com/
Offers an online Sudoku game with four difficulty levels and many puzzles. Printable puzzles, solving techniques, and handheld and board game reviews enhance your visiting experience.
http://www.sudokuessentials.com/
Offers free sudoku puzzle with a choice of difficulty level. Players can also print them out for their own personal use.
http://www.sudoku-puzzles.net/