Robin Good has posted a dynamite explanation and review of co-browsing collaboration software on his Kolabora blog. Co-browsing is a limited form of synchronization between computers that simply gets both users to the same web page at the same time. Depending on the sophistication of the software, it may enable additional actions or forced synchronization once theweb page has been displayed.
This functionality is not often exploited in webinars or formal one-to-many broadcast events, but I like to use it for one particular purpose whenever the feature is offered by a vendor. At the end of my presentation I'll bring my audience to a web page with an interactive feedback form that also contains direct hyperlinks to sites I'd like them to visit. This has advantages over a typical polling question embedded in a web conferencing presentation. People can be more loquacious in their responses, youcan design any kind of interaction and graphics that you want on the page, and you get to continue your marketing and guidance of the audience to additional resources.
Robin does a great roundup of software packages that concentrate purely on the co-browsing technology. Definitely recommended reading.