What I've done was separate sprites, but I'm pretty sure there's better ways to do it

all the particle-based stuff that people have been tossing around was based on cellular automata, which is the same sort of idea behind conway's game of life. basically you just have to determine the rules that you think will give the effect you want(if you wanted fire, for example, you could run through all the pixels that are on, make that 'particle' move up one and, via randomiser, make it move left, right, straight up, or go out).
when you said animations, though, i was thinking something completely different initially. i'd rather like to see a method that uses vector graphics and scripting for dynamic animations

all the particle-based stuff that people have been tossing around was based on cellular automata, which is the same sort of idea behind conway's game of life. basically you just have to determine the rules that you think will give the effect you want(if you wanted fire, for example, you could run through all the pixels that are on, make that 'particle' move up one and, via randomiser, make it move left, right, straight up, or go out).
when you said animations, though, i was thinking something completely different initially. i'd rather like to see a method that uses vector graphics and scripting for dynamic animations

Actually, cellular automata can get a lot more complex than that. I had a really nice program that I could show demonstrating that but some stupid loops managed to RAM clear my calc 8 times last night... 

At least I finally noticed the "backup" feature of Axe