Given the current high-ranking thread about spammy sites in Google results, it strikes me that a very simple solution would be to let logged-in users blacklist sites.
Bam, no more wareseeker or efreedom.
This would solve a lot of people's complaints in one fell swoop.
There are greasemonkey etc. scripts to do this, but they're tied to a single browser on a single machine. A global filter (like in gmail) would be so much more useful.
Would this be particularly hard to do?
Plus, we are talking about a company whose core business demands that it can identify groups of bad-faith voters. Given time, they may find a way to incorporate this data safely into the ranking data (if anyone could, it would be Google).
And I know there are extensions to do this (mine mysteriously stopped working recently), but doing this on the client-side in a way that's bound to a single browser install just seems wrong to me, especially for Google.