I think whatever system is used should attempt to avoid too much complexity. Any system can be gamed, but with complexity it can be gamed in more subtle ways. In other words, thumbs up/down with enough voters may be better than some system where the votes are weighted even if that seems counter-intuitive.

Perhaps pagerank will lead to a neural net type of A.I. system? I’m not sure if that would be good or bad.

The deep web seems more of an intractable problem because now you’re looking at dynamic pages generated from a database and some algorithm. Or just pages that aren’t referenced externally.

It just seems to me there will always be significant limitations to any search engine.