IDroo - A shared whiteboard for use by multiple Skype-users simultaneously. Features
Minuteit - Meeting manager with real time collaboration features
NoteBookCast - A real time shared whiteboard in your browser, teach, explain, sketch. For work, study, fun.
drawonthe.net - Draw on the . net is an online, multi-user, drawing website.
skrbl - Simple and easy online multi user whiteboard, start skrbl, give out your URL & start working...
Twiddla - Mark up websites, graphics, and photos, or start brainstorming on a blank canvas.