Empire magazine (online) has published a 500 greatest movies of all time, as voted on by 10,000 readers, 150 random hollywood folk and 50 film critics.
The format is a bit annoying (it means you have to click through lots of pages to see everything), but it makes for an interesting top 500.
You can probably guess #1 without much effort, but there was some surprises in the list (although with 500 movies, that’s a lot of variation in opinion and not much between them).