It's ChatRoulette but no webcams, screen sharing only. It connects the two most important things that make anything popular on the web, those that want to share with those that want to watch/read/etc.
Now go create it. Because i'll never use ChatRoulette, the concept freaks me out, but watching someone navigate their desktop, meh, it just seems safer.
To extend the idea, others can tag your surfing experience for the price of entry. You surf others build your tag cloud, said tag cloud could be used to find, via a sweeet algorithm, those that are into the same sort of things. Sure this could all be done with bookmarking services but the fun with this is the data is crowd-sourced.
Lastly, if ChatRoulette already has this as an option, it has to be screen sharing only, or no go. Drop me a line if they do.