OpenBoard - The OpenBoard software is an interactive white board software.
Tox - Send messages, files, create groups and make Tox to Tox audio and video calls. Securely.
Conceptboard - Instant Whiteboards for Teams & Projects
qTox - A Qt graphical user interface for Tox.
Scribblar - Scribblar is a free online collaboration tool that is perfect for online tutoring.
Signal - Fast, simple & secure messaging. Privacy that fits in your pocket.