Scribblar

.I may have already mentioned this resource, but sometimes there is no problem in repeating something again. This is a  Free Online Whiteboard and Collaboration Tool and it works really easily it is a multi-user whiteboard live audio image collaboration and text chat application. It's great for online training tutoring revising artwork and brainstorming. Features include a real-time multiuser whiteboard image upload and download, text chat, live audio, with no user or session limits.