Collaborative Online Whiteboards for Collaboration

Board800 is an online whiteboard. If you want to try whiteboard collaboration check it out here. Uncomplicated, simple to use.
It just works!
# An interactive multi-user whiteboard application
# Use it for tutoring, collaborative live training, brainstorming, prototyping
# An online replacement of your paintbrush application

Another whiteboard software for collaborating is CoSketch CoSketch is a multi-user online whiteboard designed to give you the ability to quickly visualize and share your ideas as images.

Simple sharing
• Anything you paint will show up for all other users in the room in real time.
• One click to save a sketch as an image for embedding on forums, blogs, etc

And, MindMeister. Extremely intuitive and easy to use. I like the interface and it’s usability. It has all of the features you may want.