Ever need to provide a list of items/products ranked by their cumulative positive and negative ratings?  It's not as easy to do it well as you might think.  Still, there may be an answer:

We need to balance the proportion of positive ratings with the uncertainty of a small number of observations. Fortunately, the math for this was worked out in 1927 by Edwin B. Wilson. What we want to ask is: Given the ratings I have, there is a 95% chance that the "real" fraction of positive ratings is at least what? Wilson gives the answer.

Read: How Not To Sort By Average Rating