The League of Extraordinary Gentlemen film, based on the Alan Moore comic of the same name. I never got a chance to see it in the theater, unfortunately (though I really wanted to), but once I acquired a DVD copy it quickly became one of my favorite movies, right up there with the Back to the Future and Indiana Jones films.
Sadly, the world in general does not appear to share my enthusiasm. I tend to attribute this to rampant Alan Moore fandom - he famously doesn't get on well with adaptations of his work, and LXG admittedly took rather a few more liberties than an adaptation can typically support.
But in this case, however, I think the changes work quite well. Certainly they don't distract from making the movie enjoyable to watch, in itself, and one of the chief delights of cameo- and reference-spotting remain intact.
Indeed, I credit The League Of Extraordinary Gentlemen with helping to form my current interest in crossovers and shared universes, most notably the Wold Newton Universe (to which the League is tangentially related).
Anyway. I've always enjoyed the movie, and was quite disappointed a few years later when LXG2: War of the Worlds failed to materialize. Almost unbelievably, it seems that the concept might still have a chance - there are some early reports that Fox is developing the League as a television show. Details at this time are sketchy - not even to determine whether this is a reboot or a continuation of the film continuity - but I'm hopeful that whatever comes from he project will be at least as enjoyable as the movie is to me.