None whatsoever. And the subject of my site attracts tons of visitors anywhere else. To give an example/compare, I get 5000+ visitors/month from stumbleupon, not to mention other places like myspace.
It provides value to online audiences, helps them quickly and efficiently find what they want. If your site is a content-driven site rather than acommercial site, then I think you can add your site to the "refined search".