The Internet Movie Database, a site that has settled more arguments than coins, is well known for its "Top 250." That "best of" list is pulled from user votes across the site, and although far from perfect, it's a pretty decent snapshot of at least the most popular films in modern culture.
Let's just say that if you started at #1 and began watching your way down the list, you wouldn't have a bad time.
But recently, IMDb has changed a key mechanism of the Top 250 - the vote threshold. This small change has apparently wreaked a bit of havoc on the list. Here's what an IMDb admin said about the changes on the boards:
In an effort to keep our charts and voting system relevant and accurate, we have made a small change to the way the IMDb Top 250 chart (http://www.imdb.com/chart/top) is calculated: the minimum number of votes needed to be included in the chart has been raised from 3,000 votes (a limit that had been set many years ago) to 25,000.
The change only affects whether a title is eligible to be featured in the IMDb Top 250 chart. Because of this, the composition of the chart will change slightly, as some titles that don't meet the threshold are excluded and replaced by others with more votes.
Basically, any movie that was a part of the Top 250 because of a high rating but had less than 25,000 total votes is gone. And some (more questionable) films have taken their place.
For instance, The Dark Knight Rises is currently the 10th best picture of all time, wit an 8.8 rating with over 178,000 ratings cast. The top twenty actually looks pretty good for Nolan, as The Dark Knight clocks in at #8 and Inception comes in at #15.
Here's a IN/OUT list that one IMDb user compiled:
Of course, the Top 250 is an ever-changing list, and as soon as some of those classics on the left garner enough ratings, they will pop back on the list.
But the vote threshold change to the IMDb Top 250 signals a move toward popularity. The films on the "out" list are, on the whole, a bit more obscure than the ones on the "in" list. Sure, The Passion of Joan of Arc may have a high rating, but it's not going to have a lot of people rating it. On the other hand, more "popular" films like Big Fish and Rain Man have filled that void.
For the most part, however, this hasn't really affected the cream of the crop. The top 25 or so of the Top 250 are pretty much unchanged, as those are the types of films that would have already easily crossed the new 25,000 rating threshold. The Shawshank Redemption still sits firmly in the top spot, followed by The Godfather, The Godfather Part II, Pulp Fiction, & The Good, the Bad, and the Ugly.