Dabbleboard is a great collaborative tool. It is basically a virtual whiteboard that allows users to create, collaborate and share. Teachers can use it for presentations, homework assignments, and study sessions.The basic version is free.
Dabbleboard is an online collaboration application that's centered around the whiteboard. With a new type of drawing interface that's actually easy and fun to use, Dabbleboard gets out of your way and just lets you draw.
Got IWBs? - this is a 3D world that kids can add to or move around ... it connects to other IWBs so they can collaborate ... and best of all it's FREE. Can also work with a Wiimote FREE home brew IWB too.