Some links with information or software about symmetry

Chaim Goodman-Strauss's site has explanations of symmetries in the plane, with pictures

http://comp.uark.edu/~cgstraus/symmetry.unit/

Kali is a program that generates symmetric patterns. The Mac and Windows versions can be found at

http://humber.northnet.org/weeks/index/Kali.html

A Java version of Kali is an interactive online version at

http://thinks.com/java/kali/kali.htm

Note: In addition to Kali, Jeff Weeks has some other interesting math software at

http://www.northnet.org/weeks/