See, but it's all about opinion. Some people honestly like Dark Knight better, because it's far more gripping and easier to get into. And those people have every RIGHT to give Godfather a 1, if people that gave Godfather a 10 are giving The Dark Knight a 1 in return. The Godfather people started this days before the Dark Knight people came in.
This reminds me of the recent articles about the netflix optimization challenge. Voting systems like imdb might be improved with some simple heuristics that take into account the absurdity of some people's votes.
If a user makes votes that are < 2.0 for a movie that the entire community for years has rated above 9.0, then probably that user's votes should all be ignored, because they are totally uninformed.
What if you assume everything is average and you give more weight toward the finally rating for those individual ratings that are further from the norm? This means people couldn't game it by following the crowd, following the crowd gives the entire crowds rating less weight.
In fact, anyone voting Godfather less than 8 should be nixxed.