I actually thought long and hard the other day about how such a system might be implemented, and came up with a few interesting ideas. Perhaps this encouragement will make me apply!
EDIT: I even wrote about it a long time ago, when I still updated my blog with any semblance of regularity. Weebly seems to be down for approximately the millionth time in the last month or so, though. I'll post the article if Weebly gets righted within the edit window.