Limnu – Create Collaborative Online Whiteboards

Limnu is a service that enables you to quickly create collaborative online whiteboards. On your Limnu boards you can draw, type, insert images, and chat with collaborators. Every whiteboard that you create on Limnu can be saved as an image to review later.

Source: http://www.freetech4teachers.com/2016/02/limnu-create-collaborative-online.html