Stoodle awhile ago. I have only tried it out with one other fellow teacher and it seems to do a very good job. It is a web based collaborative white board. I do have to say that it is difficult to use unless you have some kind of touch pad with a pen (like Bamboo Pad from Wacom) It has the basic shapes, colors and the ability to rotate objects. It does offer the use of your microphone for voice chatting. I did try out the file upload but ran into some issues. It seems to only be able to upload pictures and it would not remember my connection to Google Drive. I had to keep granting access every time I used it. All in all however, it does do a nice job and has some promise.
Give it a try and let me know what you think!!