I think that it's a great idea. One thing that I'd like to comment on: crowdsourcing > algorithms, especially with social going mainstream now.

The demo was great, but I much prefer that it's a bookmarklet instead of an inline frame. "Related sites" is not something that I need to see all the time, and it takes away vertical screen real estate, which can be annoying to some users. If you're set on using a widget, use the side of the screen to maybe house a button, expandable on click.