I've been toying around with the idea of some sort of P2P discoverability engine myself, but I don't really have the time or energy to really tackle it myself.
Just improvements on a 'recommendation algorithm' isn't enough, to me. You need to provide many, many vectors to get from one piece of content and discover something else. The more direct connections, the better, kind of like a wiki, but focused on community provided connections.
It's kind of like when I'm looking for new games for a console and I search "Top 10 games for blah" and check a bunch of list or "Underappreciated gems for blah" and check a bunch of lists, hoping for something I haven't seen before. Well what if there could be associations for just about any aspect of the content. Maybe the nodes could be auto-weighted based on how many people follow that connection, so anyone could add a connection, but the most travelled would rise to the top when a bunch of people click on it, possibly with some sort of extinction.
Anyway, it'll probably never materialize, it's just something that's been rolling around in my mind for awhile.