Follow my new blog on Tumblr and watch a new animated short ever day. Not made by me but films I found online. The main purpose of this blog is to keep track of all these great animations. These films are on different platforms like YouTube, Vimeo and Newgrounds. On Tumblr I can keep them all together in one place and tag them properly. I only embed films in high quality from legitimate sources.
Some animation goldmines I found are The National Film Board of Canada and Soyuzmultfilm. You can watch their output dating back to as far as the 1940s for free. On these channels I found films by Norman McLaren, Paul Driessen, Priit Pärn, Yuri Norstein and many more. Animation schools like Gobelins and The Animation Workshop also have YouTube channels with great student films. I also found work by Don Hertzfeldt, Sylvain Chomet, Nick Park on different YouTube channels.
Most of the classic cartoons from the United States were made for profit so sadly there are almost no films available by studios such as Disney, Fleischer, MGM, UPA or Warner Brothers. But I did found some classic Disney stuff on their official channel and also some of the classic Superman shorts. A lot of these cartoons are in the public domain but it's hard to find high quality uploads of such films on YouTube or Vimeo.
There's also a lot of great animation on Vimeo. Lots of student films but also professional work, the kind of films you can see at animation festivals.
I have made a queue of about 200 films on Tumblr that posts a new film each day. I've also tagged everything with the technique, length, country etc. so it makes it easy to find specific films.