Just while we are on topic, did you ever check out groove ? www.groove.net - it's a quit impressive thing although it's a big app. This one also work via HTTP tunnels through firewalls and proxies and allows you to transfer anything between PC's on the internet and behind your firewall. I use that to transfer files from home back to my PC at work even while I'm not there. The concept is to build groups of users which share all sorts of stuff. I found it very cool.