Scribblar - Scribblar is a free online collaboration tool that is perfect for online tutoring.
Empathy - Apps/Empathy - GNOME Wiki!
OpenBoard - The OpenBoard software is an interactive white board software.
Psi-IM - Psi-IM is a messaging program that is designed for the XMPP network.
NoteBookCast - A real time shared whiteboard in your browser, teach, explain, sketch. For work, study, fun.
Gajim - Full featured and easy to use Jabber client