I find neat stuff from y'all every day and forget to share sometimes. I have found the absolutly greatest web site for tessellations. My 8th graders are really in to it, and the designs they come up with are amazing. Anyway : http://web.inter.nl.net/hcc/Hans.Kuiper/index.html
There are 17 different symmetry systems you can download. I've put together a wonderful unit that introduces Escher and culminates with a kaliedocycle.
Hope someone out there can enjoy this.
Vicki in TN