MIT Open Courseware. A great way for students to access material that may not be presented at their level anywhere else. For that matter a great place for teachers to brush up and expand their thinking. I spent about an hour on the combinatorics course developed by an MIT student for high school math students who are 'bored' by high school math classes. If you are interested, it pushed my understanding pretty quickly!
Another persons effort to organize Web 2.0 applications, so you and I don't have to. I think it's a pretty good list, and worth looking at if you are looking for some new tools. I particularly like earth album http://www.earthalbum.com/
Welcome to The Center for Teaching History with Technology, a resource created for teachers looking to incorporate technology into their classrooms! THWT aims to help K-12 history and social studies teachers incorporate technology effectively into their courses.