so. a quick javascript gravity sim.
it didn't come out quite how i was hoping because i had to dickey with the gravitational falloff to get somewhat stable results. typically gravity falls off as 1/(R^2), but the simulation here is actually using something more like 1/R^1.1
why 1.1 and not just 1 ? - it ended up prettier. i need to go back and recheck my math and such.
along the way i made a handy javascript 2D vector class tho, if anyone's interested in stuff like that.
the bodies are heavier the bigger their number. apparently it only works in firefox. sorry, ie.