UPDATE 1/8/2015: I Remember This Movie, an entire website dedicated to solving mystery movies, is now open! Please move all your movie questions there. Comments will be left open here for the time being, and we will not stop anyone from posting here. However, we are removing the list of unsolved movies, since it makes no sense for people to keep guessing about movies questions that were asked years ago. Thanks a lot, this page has brought us a lot of traffic over the years—which is precisely why we thought the concept deserved its own site.
UPDATE 11/5/2013: I Remember This Movie, an entire website dedicated to solving mystery movies, is now open! You may continue to post your questions here for the time being, but we prefer you use I Remember This Movie and plan to move all our movie-answering operations there by 2015.
This page has become very popular, which is gratifying. Unfortunately, it has also become a pain to maintain, which is not. As a solution we have created an entire new site organized around the concept.
I hope I Remember This Movie will prove easier to use: your mystery movie will now have its own post to which people can respond if they have a solution. I think this will be much better organized and easier to follow. We also keep a leaderboard showing how many movies each user has solved, and hope to add prizes at some point in the future.
I will keep this page up for the time being while we work out the kinks, but I encourage you to try out I Remember This Movie instead.
As a heads up, I find that the badmovies.org “What Was That Film” board can be the best place to ask these sorts of questions, particularly if the film your looking for is in the horror or science fiction genres. It may be a good idea to ask there as well.
Some idea of when the movie might have been made is helpful. If you saw it in 2005 then say so so we won’t suggest movies made later. Remember, something like “I saw it when I was six” isn’t that helpful because we don’t know if you’re 16 now or 60!