Here's another tool from The Collaborative Web.
Thinkature is a collaborative VISUAL workspace that can be marked up and chatted in using synchronous communication. You can place images and text in the workspaces and connect them in real time. The homepage's workspace is live so you can experience how easy it is to create, move, edit, draw and connect your ideas. Thinkature's workspace reminds me of the UPS television commercials.
When I go back and think about some of the other collaborative tools I have explored I think that each could have a different use. Mindmeister uses text to create a visual map with real time collaboration. I liked Mindmeister as a mapping tool and I could see it used as a tool by a teacher in a classroom discussion. Writeboard is definitely a collaborative writing tool. It is does not allow real time collaboration, however, I can see Writeboard being used to create a collaborative document, i.e. long range plan, which may not need a lot of real time collaboration. Backpack and Stu.dicio.us are two online tools where note taking, to do lists, images, etc. can be shared with others, though, not in real time. These two applications seem to be individual organizational tools which could be shared with peers. Thinkature is a real time tool that could best be used for brainstorming, laying out a new organizational chart, creating a floor plan, planning tool, etc.