About 2 years ago now, when I was first adding the BitTorrent support to GetRight, I wrote a proposal for how others could do the same combining of HTTP/FTP downloads into a BitTorrent download that I was adding into GetRight.
It's been edited and updated a few times, the original is here:
As I've been working on other things and not paying attention, it's become a quite accepted standard for BitTorrent clients. All the main ones, including the BitTorrent.com client itself, now do it. Pretty awesome!
I've just written it up in the format for the new "BitTorrent Enhancement Proposals".
I get to add to my resume: "Invented the WebSeed mechanism that has become part of the BitTorrent protocol standards." (Draft in the proposals right now...but a lot of clients have done it.)