Computer Animations using Maple  
Watch Out for that Last Step, by Alex I. 
Triangle Fun  
Proof of Pythagorean Theorem 

Logic Puzzles:  I'm Lying 
Map Coloring 
Cryptography:  Dszquphsbqiz 
Platonic Solids and Euler Numbers  
Stellated Icosahedron 
Counting, Probability and Infinity
Math Games, Puzzles and Contests