There's an offer they have at the moment where you can get a few weeks subscription free of charge. If you're sneaky you can then go to the archives section and download all their old editions...
The College now has a student subscription to this site. If you direct students to access it with the username Sheldon and the password College they can access it at home. Either that or you can use it in the classroom.
Here is an example of a social network in education. I heard it recently called 'network learning.' Ning is the best platform I've found, although the adds can be annoying. (>)_(<)
THE best presentation creation tool I've ever seen. Once you get used to it you can create awesome presentations and the free access section gives you quite a bit of storage. You create them online and then download them as a package to play anywhere. Very cool!