If you plot all movies by their number-of-votes on IMDb and their rating on IMDb, you get the chart below. Movies with more votes usually have a higher rating.
I was interested two things:
The answer to the first question is: there are no unpopular good movies. The cluster of dots on the top-left (in red) are not movies -- they're TV shows (Band of Brothers, Pride and Prejudice, Arrested Development).
The answer to the second is: there are 9 really popular lousy movies.
It's interesting that every single one of these had a huge budget. (Perhaps this is understandable: more people would see a big-budget film and vote on it.)