Check out this Climate Change project on ePals. It's free and helps your students collaborate with students in another place. They can use safe and free SchoolMail to communicate with the other students, if you wish.
I do a webinar called ePals 101 about the free tools. Sign up for one at: http://epals.101.sgizmo.com and learn how to get going with this! Look at the projects too: http://www.epals.com/projects
And you can use ePals tutorials on your own, if you want to get started now: http://bit.ly/learnePals
Good luck! (And for yourself, read Hot, Flat and Crowded. I heard Thomas Friedman, the author, speak last night, so I'm going to grab his book now.)