This page seems to be a pretty comprehensive list of all such software out there. I only have experience using stuff like Groove and Sharepoint that don't do exactly what you want, but maybe some other people have used some of the more niche stuff that is listed. Netmeeting might also be useful in terms of letting you communicate visually (i.e. via Whiteboard and video conferencing) but they don't have such good tools in terms of logging what occurs for a permanent record. There is also a tool that Google uses internally as a sort of quick wiki that lets people create websites easily to flesh out their ideas. It is called SparrowWeb and there is a demo of it here. It used to be free but now I'm not sure what the licensing is like.