A couple weeks ago what we did in class was use IRC and wiki. Not really sure how much I can say on it, as neither were really new to me. I think IRC is a great way to be able to meet and talk to people that you would otherwise not get the opportunity to do. It’s more immediate than forums which helps to add the possibility of more details in a conversation.
Wiki, of course, is a good tool for documention a project. It’s easy to edit, and it can be opened for anyone to edit, which means that there are less barriers for new sources of information being introduced.