My stuff:

Conway's game of Life
Counting Horizontally Convex Polyominoes (in the Journal of Integer Sequences)
Reducing a Set by Subtracting Squares (with Michael Kleber, in the Journal of Integer Sequences)
Prime maze puzzle
Packing the refrigerator door

A Two-dimensional Cellular Automaton Crystal with Irrational Density (with David Griffeath):

Postscript file of article, in Zip format    
Patterns and software

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Links to other people's stuff:

Frequently used links

Neil Sloane's On-Line Encyclopedia of Integer Sequences
Eric Weisstein's Encyclopedia of Mathematics
WWWebster Dictionary
Mathematica documentation
Math Reviews
Doppler radar images
Zip code lookup
Putah Creek water level

Mathematics
Puzzles
Skating
Juggling
HTML
Local info
Miscellaneous