This is a "semi-orbital" particle cloud animation that I've created around three years ago (2010) but have now
updated and optimized to use requestAnimationFrame etc.. It's a Canvas based animation that uses I wrote from
scratch without using any libraries (except jQuery, but it can be easilly rewritten to not require it).
The particles are randomly generated during the initialization stage (colour, size etc.) and then are non-randomly animated using quasi-physics that actually aren't similar to anything in real life.
By deafult the particles will follow your cursor (or finger on touch-screen devices). You can click to repel the particles.
Demo with 10000 particles (warning, can be really slow!)