Web Brush – Active Colloboration tool
Web Brush is an online multiuser web application which can be used for the creating/discussing diagrams, flowcharts, schemas etc., Using WebBrush you can share diagrams/texts/images with your friends. It has a chat panel for sending text messages. WebBrush can be very well used for educational purposes.
BTW it doesnt work with Firefox and I was forced to use IE5.5+ 😦