Online Rubik's Cube - Guaranteed to keep you online past bedtime! (Advanced Topic - Notes on the Math of Rubik's Cube)

Famous Puzzles - Exercise your brain with problems that have kept people guessing for centuries! (Math Forum)

Cut-the-Knot Interactive mathematics miscellany and puzzles. (Alex Bogomolny)

	Fractals	Chaos	Tessellations
	Spirograph	Knots	Origami
	Conway's Game of Life	Mazes	Lissajous Lab
	Roman Numeral Calculator

Articles

American Mathematical Association Online columns (some monthly, some more often) on recreational math.

Scientific American: A Century of Mathematics How can we evaluate what has been accomplished and guess at what's to come?