Kali is a program that lets you draw symmetrical patterns based on any of the 17 wallpaper groups, as well as several frieze and rosette groups. And it's tremendous fun!
Instructions for using Java Kali
Kali was written originally for the Silicon Graphics (SGI) workstations by Nina Amenta. In April of 1995, Jeff Weeks modified the program to run on Macintosh computers. In September of 1996, Mark Phillips modified it to run in Java.
Thanks to The Geometry Center (University of Minnesota) for the use of this applet.