Ever since I was introduced to the site, The Dark Knight has been the #1 global favorite. I don't mean to deride the movie--the Batman fan in me loved it--but I think this reflects the demographic of Flickchart's users more than anything else. So, please, if you have even a passing interest in movies (and are looking for a new, hyper-addictive way of spending your time online), visit that site.
The other site that has my attention of late is I Check Movies. You know all those Top Movies lists that get published all the time? (Like the ones I've posted in this very blog, for instance.) Well, this site compiles those lists and lets you check off which movies you've seen. The nice thing is that, once you've checked a movie, it is checked on all lists where it is present. So, let's say you're going through the American Film Institute 100 Years...100 Movies list and you check off that you've seen Lawrence of Arabia. When you go to the IMDb Top History movies, you'll find that Lawrence of Arabia is already checked. There are quite a lot of lists, from AFI, IMDb, the Academy Awards, critics like Roger Ebert, magazines, websites...pretty much any source.
I Check Movies is really geared toward the list-oriented movie fan. More casual movie fans will find it less interesting. There are virtual awards posted to recognize your progress. Even with my limited number of checked movies, I've been awarded three bronze trophies for my progress to date. I'm hopeful that they will add more lists soon, partly to expand the appeal of the site and partly to give me a chance to cover some more ground based on what I've already seen.