Archimedes' Laboratory - Recreational mathematics including puzzles to make and solve, tessellations, geometric puzzles, optical illusions, and curiosities. Puzzle Contest Center - Riddles, brainteasers, cryptograms, anagrams, and logic puzzles. Compete in eight new contests monthly. The Grey Labyrinth - A beautifully illustrated collection of puzzles, riddles, and paradoxes. Features a changing "unsolved puzzle" plus three years worth of previous puzzles. Puzzability - Some real mind benders here. National Puzzlers' League - Crosswords and other word puzzles and games, samples; monthly puzzle magazine; 800,000 word searchable list. Braingle - Includes a huge collection of user submitted and rated brain teasers and riddles. It also has a message board and some unique multi-player games. Planetarium - An on-line puzzle story in twelve weekly installments. Abnorm's Conundrums - Easy, medium and difficult brain teasers without answers. Bill's Brain Teasers - A collection of visual and linguistic riddles. iRIDDLER - Challenge your mind with free online riddles/puzzles, logic games, brain teasers and view optical illusions. Say What You See! - Collection of visual brain teasers which can be solved by saying what you see. Just Riddles and More - Riddles, illusions, puzzles, and brain teasers. PedagoNet Brainers - Over 60 brain teasers to enhance your mind. Professor Tangent - Have fun with games, puzzles, brainteasers and humor as you learn about logic and analysis. Rec.puzzles Archive - An archive of many popular puzzles from the rec.puzzles newsgroup. All-Star Puzzles: Logic Problems - Collection of logic problems to solve. Printable. Curiouser.co.uk - Paradoxes, puzzles, games, optical illusions, poetry, curious facts, and quotations. Had To Play On - A community based site with competitions, challenges, awards, a help centre, forums and games. Word Juxtapoz - Word puzzles, riddles, rebuses, brain teasers, mazes, cliparts and pictures. Eyetricks: Brain Teasers - Weekly puzzles and archives. BrainBoggled.com - A collection of math, logic, and word puzzles. BrainBashers - Brain teasers, puzzles, riddles, games and optical illusions. Zuzzle Puzzles - Collection of puzzles including riddles, logic puzzles and sequential puzzles. Pzzls - A collection of logic puzzles, riddles and brain teasers. Thinks.com - Recreations for active minds including games, puzzles, math, words, images, books, software and web guide. Puzzles Without Rules - Free, updated, original abstract puzzles for advanced puzzle-solvers. Includes current unsolved puzzle and archive with hints and solutions. Brain Teasers - Brain teasers, riddles, logic puzzles and problems, paradoxes, optical illusions, IQ tests and logical games. TechInterview - Answers to technical interview questions, programming problems, and brain teasers. Puzzles & Computer - Pascal Huybers presents information about a variety of different puzzles. The Logic Zone - Collection of logic problems, logic puzzles and cryptograms with answers. Graded levels of difficulty including some especially for kids.