Since Particles’ve been a crazy not so long ago (and still are really), I thought I might aswell throw mine up here.
This one simple sprays out instances with all the values of gravity etc.
The emitter is draggable, with the option of having it move around randomly (click the top right button to toggle)
http://www.avalon-rev.dk/junk/particles/particles.html
(only works in IE for some reason)
source: www.avalon-rev.dk/junk/particles/particles.zip