DSANDLER Skyrocket is nice, too. However, I find some of its 3D effects (for example, the constant swooping around of the camera) a little distracting.
Pyrotheque has some great graphics and visual effects, but it's not trying to be flashy; I designed Pyrotheque to more accurately mimic the style and tempo of the original Mac fireworks screensaver: Pyro!, by Bill Steinberg and Steve Brecher. In particular, Pyrotheque's 1-bit mode is, for me, an awesome timewarp back to 1988. I hope others enjoy it too.
(Version 1.0.1)