Particle effects, usually made by code.
green circular particle scramble / swirl by Sean Free PRO
HTML Canvas particles with collision, Sattelite particle effects, created by Marko Å valjek
A nice colorful effect called Plasma Particles (by Marko Å valjek). Make sure you change the settings a bit in top right co ...
Eye laser experiment by Lukas Haring
A nice particles effect; rainbow Falls (with force), like matrix colored letters. Created by FlyC.
Animated bubbles background created by Ben Hodgson. This doesn't use flash, it is HTML based.
Hyperstellar particles animation created by Tiffany Rayside