Here is a flash physics simulation I built few months back when I was fiddling around with flash, conclusion: flash can yet still be powerful enough to make some really neat games with interactive physical simulations, it uses an euler integration method with step function (duh!) blah blah blah, anyway, here it is,
note: you can drag the balls around
Edit: I've removed the flash from running within the blog environment due to some technical issues. Please click the below link to use this Flash Toy