Before it got killed by Amazon, one of the best things about LoveFilm was that it showed the distribution of user scores for each movie. For many movies the distribution was normal (peak in the middle) and those movies were usually "OK" ... but the interesting ones were the "marmite" movies with lots of 0s and 5s. Both sets would have the same average score, but you could gamble on the marmite ones and maybe get a great movie with a 3 average.

(I also try to avoid reviews before watching)