Scriblink and Etherpad Assignment

As I played around with Scriblink I learned that it is a free digital whiteboard that can be shared with several users at the same time. It has several tools such as math symbols, uploading images, typing and drawing tools. I liked the ability to upload images because the user then can draw, edit, or use it in examples.
The Scriblink could be best used in the educational field for tutoring or homework help from home. For example, if you upload worksheets or problems students are assigned they then could ask specific questions and you could demonstrate steps or give explanation via writing. It also has the ability to do voice conferencing.
As I explored the site I also found that this free service could be purchased and used for personal websites.

I also explored Ether Pad. This is also a web-based tool but is different because it has the word processor format instead of a whiteboard. This service also allows multiple users to use it at the same time in real-time. The other users signed on are shown on the right side. The individual user can select a desired color to represent their contributions to the word document. This way all users contributions are noted and displayed.
I see that this web-based word processor could be used for students who are working on a group project but couldn't all meet at the same place. The students can log on and collaborate via Ether Pad. It can also be used in team meetings and for drafting notes for an up coming conference or meeting.
I find that limitations for both collaboration tools is that all users must have access to a computer, be on simultaneously, and or understand and have ability to use the site.