I was chatting with a former colleague Jake tonight and he mentioned a very interesting project he was a part of in grad school at UNH.
His class learning Spanish met with a Spanish class learning English on a Wikispaces wiki. Each learner posted projects in the language they were learning and edited and critiqued the work in their native language.
There were several topical assignments that the classes sorted out in both writing, video and audio formats.
The wiki is in Spanish, but it looks like a very interesting project for all language classes.