Its goal is to help K12 educators find and use K12 appropriate resources on the web. You can try it out for a free 14 day membership by registering with this site. They say it takes 24 hrs to get a password but mine came through in 3 hours. They have participants in 97 countries. National Science Teachers Association is another good resource Computer Curriculum Corp - This multimedia educational publisher has a rich site.
Teachers can participate for free in something called the Project Zone .
It includes thematic lessons, coordinated to topic and subject. There is also an online teacher chat which offers opportunity to collaborate with other teachers. Journey north - From the Annenburg Math and Science folks. This group's goal is engaging students in a worldwide study of wildlife migration. Kids get to contribute field observations from Alaska to Mexico.