Here is a great way to find teachers (in your area of teaching) who use twitter for collaboration! You will need to start a twitter account (http://www.twitter.com), but it is easy to setup and start following people. What a great resource!
This page has a long listing of Wiki examples for all subject areas. There are a good number of science example. An easy way to find them is to Click on Edit->Find, type in Science, and keeping hitting enter (or find) to get through the page.
You'll find a lot on this site, including a large number of resources, textbook reviews, powerpoint tips, tutorials, templates, resources for multimedia approaches for teaching biology, etc. Be sure to click on the About tab along the top of the page for additional information and the purpose of this bioblog. Great stuff.