Mathematics

• Wolfram|Alpha
• Pi through the ages
• List of Math Resources
• Online Encyclopedia of Integer Sequences (OEIS)
• Inverse Symbolic Calculator
• Math-related links
• Wallpaper Groups -- the 17 plane symmetry groups
• Tessellation page
• Compendium of Fractal Tilings
• The Matrix Market Deli -- generates matrices
• Mathematics in Movies
• Test your Telepathic Skills

Puzzles

• MathPuzzle.com -- Ed Pegg Jr.'s math puzzle page
• Puzzles.COM
• Meffert's Puzzles (Rubik's Cube-style puzzles that you can buy)

Games

• Cribbage Rules

Text-based Computer Games

• The Colossal Cave Adventure Page

Computer Science and Related Links

• Retro Computer Museum
• Scheme
• HTML
  • W3 Schools
  • HTMLSource
  • Special Characters
  • HTML tag reference
  • More HTML info
• Wonder Works
• Emacs VM mail reader
• X Screen Saver
• JWZ's page
• LWN.net (Linux info)
• Magiq Tech