A super nice member!
SkyDrive from Microsoft is a collaborative office suite. Just as with many other online office suites, Skydrive allows for a collaborative environment for students and teachers. All documents can be displayed online or downloaded in Microsoft's default format, which is the most widely accepted format available today.
Google Earth is a tool that can be used in many subjects from math to language arts. The user base is very large providing a wealth of lessons and ideas. In addition, it's free and cross-platform.
Great courses for learning how to program. Once an account is made, students can track their progress through the linear courses. Lessons are short allowing them to be done as an extension or club.