Aye, metaballs are pretty cool! I'm using Maya a lot more lately, and there's these things called "Emitters". They are particle-dynamic emitters, meaning they shoot out particles at adjustible rates, flows, directions, with gravity and all kinds of forces that affect them. Ultra-realistic, and very powerful... So in Maya 6, they allow you to shoot off "Blobbies", which are extremely adjustible Metaballs... This shot is part of a 10-second animation I'm nearly finished with, rendered in Mental Ray for Maya. These Blobbies interact gravitically, and flow along and collide with every surface, with dynamic and static friction, weight, and velocity as well as gravity! The only thing I've NOT found possible so far is surface tension, but I'm sure it's there somewhere... Maybe we'll see something like this in Bryce soon, I just thought it would be cool to show what's possible with Metaball mathematics!