Cool Math Links

Do you need a mathematics dictionary? http://www.mathwords.com/a_to_z.htm
Do you need to convert old units? http://www.calculateme.com/

Some Illusions

This is in Spanish, but has a huge selection. Click on the Eye to open http://www.ilusaodeotica.com/
This is in Italian but has many excellent images http://www.illuweb.it/
The Mighty Illusion Page http://www.moillusions.com/
Optical Illusions Etc http://illusionsetc.blogspot.com/
Amazing Art http://members.lycos.nl/amazingart/E/index.html
Japanese. There are heaps of eye popping designs http://www.ritsumei.ac.jp/kic/~akitaoka/index-e.html

Puzzle Sites

The Archimedes Lab http://www.archimedes-lab.org/ or http://www.archimedes-lab.org/index_curiosities.html
The Ultimate Puzzle Page http://puzzle.dse.nl/index_us.html
Interactive Mathematics Miscellany and Puzzles http://www.cut-the-knot.org/index.shtml

More Fun Stuff

Lots of different activities http://www.coolmath.com/
Wonders of the World: Facts and Figures http://hillmanwonders.com/
Interactive Mathematics Activities http://www.cut-the-knot.org/Curriculum/index.shtml#illusions
The Pifactory http://www.friendsatwork.co.uk/index_old_01.html
Mathematics Fun, Fact, Fiction, Function, Fantasy http://www.lifesmith.com/mathfun.html