Don't know how to say this, but here's what i think :
Torrentbd users are all using broadband services interconnected with bdix. We download things and share via torrent to utilize local speed. Now we all have capped "internet" speed. I use a 512 kb smilebd connection, someone else use 2mb connection. Now imagine a swarm of users sharing "internet" speed through local bdix. Someone's computer is idle so his internet speed is distributed.... kind of thing.
I use two broadband line ( one smile 512 kb and another 32kb global ). Recently i am using connectify dispatcher and this amazing software now let me use both connection speed at once. If i use idm/torrent where multiple connection can be established with server, i can use both the speed and get around 80KB/s. So, that imaginary internet sharing software can sit and forward someone else's threaded connection , get the packets , send to the target user through bdix... and so on. There can be a DHT table kind of thing that can track users, total shared internet and average the speed throughout the swarm. A 2mb/s user will always get his nominal 2mbps speed, but as he is a part of the share, he will get extra whenever its available and vice versa.
I never heard of this kind of softwares available / used by community. Anyone knows any ? Would be kind of cool you know.
And yes , i dont know how p2p file sharing network works , and i have a very limited knowledge over sockets and ip etc. So above statements can be a bit dodgy