Already talked a bit about the Adventures of Prince Achmed. I thought this old music video was great, it's a 1933 animation for the composition of Night on Bare Mountain. Best to go to the Youtube Page and watch it in 480p, but if you don't want to just press play on the video blow.

Really love the thought and style put into this film.

not about animated films, but here's an article about Charlie Chaplin's early films. interesting stuff:

http://www.cnn.com/2010/SHOWBIZ/Movies/01/29/charlie.chaplin.restoration/index.html?hpt=Sbin

Nice, maybe I can get a much nicer version than the collection we have on VHS. He is pretty damn influential.

Here's something that's not that old, it's only 25 years old. But it's I think Japan's first Surrealist animated film. Very little dialogue, a bit confusing because lots of metaphors. There's no action, it's a bit slow paced, but I still found it interesting especially since it's one of the first for japanese mediums.

This is a 5min preview and if you choose you can watch the full thing at their site.