Now for some old school:
All Quiet on the Western Front (1930)
A Day at the Races
Duck Soup
Monkey Business
Nosferatu (1922)
Safety Last!
Honorable Mention: MANOS The Hands of Fate!
And also, anyone that's a fan of silent movies should check out "The Call of Cthulhu"(2005). It was released last year on DVD as an independent release, and it's a B&W silent film that tries to recreate the style in which a movie would have been made of the H.P. Lovecraft story at the time it was written. Very good stuff.