Scribblar - Scribblar is a free online collaboration tool that is perfect for online tutoring.
NoteBookCast - A real time shared whiteboard in your browser, teach, explain, sketch. For work, study, fun.
OpenBoard - The OpenBoard software is an interactive white board software.
IDroo - A shared whiteboard for use by multiple Skype-users simultaneously. Features
Conceptboard - Instant Whiteboards for Teams & Projects
Haiku Deck - Presentation Software that Inspires | Haiku Deck