The thing is, the dns-backtracking-browser-plugin sounds like a simpler and more doable approach compared to anything else I've heard of. Any more elaborate approach would have to settle who owns a domain and that's not any easy thing for the present system.
It would certainly need to be system/browser specific but otherwise doesn't sound hard. Indeed, I could do it in a couple weeks and a really smart person could do it in a day.
Obviously it's a stop-gap. The distributed peer-to-peer client featured here a couple of weeks ago is a far more robust solution. (see http://news.ycombinator.com/item?id=1985431). That would include a system fairly similar to what you describe.
