XDA member Dysgenic was apparently unsatisfied with his current Android boot animation - so like any good Android lover, he decided to do something about it. The result: an ever-expanding list of absolutely awesome boot animations. Just take a gander at these two (there are currently 8):

androidglow androidparticles2

Installation is essentially comprised of three basic steps: first, download the animation(s). Second, rename the one you're using "bootanimation.zip." Finally, use ADB to push it and overwrite the existing animation.