rohitj - 1:55 pm on Aug 8, 2006 (gmt 0)

The database loads on a project like that would be overwhelming. Not to mention, it would only be useful to be able to subtract sites. In order to add sites, you have to have a means to find them and, hence, the whole point of a search engine.

That being said, I could also see a secondary market come about wherein people sell their "subtracted" sites which were spammy in their opinion. People with a reputation would be in high-demand to show their subtraction list. Would be kind of cool unless you're one of the unfortunate publishers to be considered spammy.