The Jybe extension is a neat collaboration extension for a web site. For you freelancers out there, this may be what your looking for when showing your web site to a client and they get lost with a page element or section.
This extension uses a central server in conjunction with the extension in either Firefox or IE and runs off of a "session" concept. The sessions are password-protected, the ability to pass control to another presenter, and you can have collaborative scrolling and text entry.
There are some problems with the extension. The extension always connects to a public server. If that server isn't up and running, the extension will fail, rendering it useless.
Another downside to this extension is that they need to update it. It only works on Firefox 0.7 to 1.0. They don't even have a version for 1.5 or higher. Bummer.
If you are doing remote demonstrations with a client, this extension will be valuable to you, uses IE or Firefox, and comes at a great price (free), so long as you have the right version. :-\