This is what a Scribblar whiteboard looks like. Both the student and the tutor are able to write on the whiteboard in real-time, and communicate using the microphone. No softward download is required, and registration for Scribblar is free. The student is able to save the individual pages on the whiteboard and download it to a local computer for future reference.
See the guide to using Scribblar at: http://www.bucks.edu/media/bcccmedialibrary/tutoring/documents/GuideUsing%20Scribblar.pdf