One of the coolest implementations of WebRTC is a project my friend launched called PeerCDN (<a href="https://peercdn.com/" rel="nofollow">https://peercdn.com/</a>) - basically allows you to reduce bandwidth costs by leveraging the resources of active users on your app.
Welcome to 1991, Web browsers.<p><a href="http://en.wikipedia.org/wiki/Direct_Client-to-Client" rel="nofollow">http://en.wikipedia.org/wiki/Direct_Client-to-Client</a>
This is neat. I've been meaning to do something like it myself for fun. I'd be far more interested in one that just let's you drop a file and gives you a URL for your friend to visit with no other steps. Having one of these services that does the transfer directly peer to peer without accounts or setup steps would be great.
Opera Unite was trying to do peer-to-peer centrally indexed file sharing as part of their offering I think (<a href="http://unite.opera.com/application/132/" rel="nofollow">http://unite.opera.com/application/132/</a>).<p>I blogged about it back in 2009 anyhow (under the self-effacing title of "Opera is about to change the world?!"!).
<a href="http://sharefest.me" rel="nofollow">http://sharefest.me</a> is another file sharing platform, works both on chrome and firefox (but not inter-operable yet).