I wonder if a reputation system could be applied to, say, Amazon book review ratings. It would be a more complicated calculation, but what if a star rating could be weighted according to those reviewers with whom I seem to agree? That data could be gathered by what I bought in the past and who reviewed it, and could be further refined if I gave my own rating later. Then instead of every rating counting equally, ratings for new books I'm considering are biased towards the opinions of those like-minded reviewers.
Mokalus of Borg
PS - Yes, it is complicated.
PPS - And I'm not totally sure it's necessary.