David Daniels produces animation by the process of stratacut animation. Once you know how it's done, the difficulties of this art will blow your mind. From vimeo:
Strata-cut animation is most commonly a form of clay animation in which a long bread-like "loaf" of clay, internally packed with varying imagery, is sliced into thin sheets, with the animation camera taking a frame of the end of the loaf for each cut, eventually revealing the movement of the internal images within. Wax may be used instead of clay for the loaf, but this can be more difficult to use because it is less malleable.
Stratacut is created only through an in depth understanding of space-time, because in stratacut, you build your imagery not just in X, Y, and Z space, but also considering time as a dimension, and the most important one. Students who have undertaken the challenge of creating stratacut animation will tell you, it is not for those unwilling to bend their perception of animation, and time in the process.
Next, consider what is involved in designing and building that "internal imagery" in the clay loaf, both in the artistry and timing. Now that you have the process in mind, enjoy some clips of Daniels' work. You will probably recognize some of these, but you'll appreciate them more knowing how they are done.
Blinking Eyeball Demo
(YouTube link) First, a little demonstration of just one element of a video -an eye that blinks, from Daniels' tutorials.
Journey Through A Melting Brain
(vimeo link) And a reel of professional work samples from David Daniels.
"This is sometimes harder than it looks." —David Daniels
Oh, it looks hard enough! Daniels has a website in which he shows you how to begin doing your own strata cut videos. Link
Read an interview with Daniels and see more examples at Art of the Title. Link -via Metafilter