Well the online whiteboard market seems to be heating up with another impressive offering. I wrote about Dabbleboard last week, and now only a week later I've just spotted Scriblink which takes things a step further and includes VOIP, text chat and provides users with link to their online board.
I just created this quick labeling activity using an image from Flickr creative commons
The site has now generated me a link to this page to share my whiteboard online.
Click here to check it out live (Takes a little while to load)
All this seems like interesting stuff for anyone involved in online synchronous tutoring.
Looks like it's free too!
There's a more detailed description of the features here.
Hope you find this useful.