C4 have done 1 on British box-office receipts which Gone With The Wind won I think - nothing to do with quality of film of course.
They also did a top 100 which I think Star Wars won - trouble with that was that they chose the shortlist on which we could vote, and it wasn't a universal vote.
There are various other top 100s out there, and even a top 1000 on the 'They Shoot Pictures Don't They' website.
For all it's faults, the best meter of public opinion may be the IMDB top list, simply because it includes every film ever made and gets lots of traffic. It has The Godfather at number one I believe.
But as is said earlier in the thread, there is almost certainly no way to absolutely decide what the best film ever made is, because the criteria for such an award differs from person to person.
My favourite film is probably Vertigo.