Open Culture has a list of 70 free animated films such Tijuana Brass; a precursor to modern music videos, this Oscar-winning animated film by John & Faith Hubley and many others. Some of the links don’t work due to copyright laws and bla bla bla… go check them out!
From the site:
Watch over 70 free animations online. The collection features some classics, plus some modern gems. You’ll find a number of animations of literary classics in the mix too. For more great films, please visit our complete collection
You can see the full list here: http://www.openculture.com/free-animated-films