Have you tried Google Wave? I asked my husband to send me an invite, so I can see if it will be a good collaborative space for a project I am working on now.
I'm still trying to figure out how best to use it.... the user interface looks like a lot of fun, but it is a little hard to navigate (or at least it doesn't seem all that intuitive to me).
So right now my wave is more of a ripple.... but we'll see!
