This became my 500th bookmark on Diigo thanks to Jim Batchel. If you are trying to figure out whether blogs/wikis/ning is better for your students, it looks like you can have it all and more at ThinkQuest! You need an account to sign in but under the Projects tab you can look at some public video tours of its features. ThinkQuest is a protected, online learning platform that enables teachers to integrate learning projects into their classroom curriculum and students to develop critical 21st century skills. It includes a project environment where teachers and students engage in collaborative learning; a competition space where students participate in website development contests; and the award-winning ThinkQuest library, a learning resource visited by millions.
Excellent site with online math manipulatives. Would be great on the SMARTBoard. A digital library containing Java applets and activities for K-12 mathematics
This large library of free photos was contributed by students, teachers, and amateur photographers. This should be a relatively safe place for students to search photos.
This section of flikr teaches social studies by inviting you to comment or tag photos. I searched for Titanic and found some very poignant images with comments by the people who had viewed the picture already. This could be a very powerful learning tool.