Every week Tor.com presents two animated short films as its Saturday Morning Cartoon series. And every week I am impressed by the extremely and consistently high quality.
Some of the more recent computer-animated ones are startlingly well-animated - as good as a Pixar short or better in terms of technical quality, but not always meant to appeal to the mass audience Pixar depends on. I'll admit that at first I was provincial enough to be somewhat surprised at such technical accomplishment coming from French or German production companies I'd never heard of, but I'm over that now.
Some shorts are several years or decades old, but beautifully made.