Google tried this. It was called SearchWiki.

http://googleblog.blogspot.com/2008/11/searchwiki-make-searc...

Or was called SearchWiki. It turned out that nobody liked or used it, so it was removed.

I liked the small satisfaction I got from 'X'-ing out spammy sites!

I would've used that more if X-ing them out kept them out! Afaict, it only removed them from that particular search, and if you searched again, they'd show up again.

I believe it only had an effect on your personal view of Google. Otherwise, it would have been abused by competitors and 'SEO experts'.

blekko lets you slash out individual sites from the search results. The exclusion just applies to you so spammers can't downvote reasonable sites. Has been popular to eliminate ehow.com from results. ehow isn't enough over the line for us to ban from the crawl entirely, but a lot of people don't ever want to see them in their results.

we're still in private beta, but happy to give invites to anyone here who wants one. just email me rich at blekko.

Do you have a predefined list of 'These are SEO sites which add no real value' sites which I can include by default?

That's a good idea, thanks. We'll add something along those lines...

Then the spammers would use bots or cheap Chinese labor to downvote their competitors. It would just move the problem down a level. For this sort of thing to work, the curators must be trusted, which is expensive.

Such an engine might be worthwhile to a small subset of users, though.