I have been using Google docs successfully in my classroom.
We were trying to use Skype with an astronaut from NASA but at the last moment he was busy with the shuttle flight and were not able to talk to him.
Last week at Teacher U technology blitz, I learnt about Edmodo. I liked it and in the coming school year will try and use it.
I have used Poll Everywhere and that is also a good tool to use with the students.
Next week I have a class on Diigo. Lets see what that has to offer. If it is easy to set up and use then I can try that out to.