I wanted to use it for group projects at school, as it seemed like a really good combination of IM (interactive and fast) and email (permanent and viewable at any time), integrated with the ability to share documents, etc... It would make that kind of collaboration so much easier, but it never worked out because no one in any of my classes had heard of Google Wave. I did get to use it a little bit at work, and was a little disappointed by it, but I don't think there's a better tool for coordinating a small group.