Well, does it have to be an invisible global blacklist? Would it be possible to create personal blacklists and have one for each user? I mean, Google already customizes search results for logged in users, so this wouldn't be too far of a stretch.
> Would it be possible to create personal blacklists and have one for each user?
I think that's pretty clearly what we were talking about. There are invisible global blacklists already, as should come as no surprise (even if you haven't run into one of the hits omitted thanks to the DMCA).
