Hmm, could you do anything but a ragdoll effect? Would there be a way for the character to hold up some of its limbs so he didn't go completely limp? Or maybe if a rolling object collided with him it would take his legs out from under him and cause him to fall on his face.
exactly what I was getting at with the motorized limbs. I'm not sure how difficult it would be to program, but yes, that's exactly the type of thing I'd want to see. or on a simpler level an arm that could try to pull an object or character that was trying to pull in the opposite direction. a clockwork gear that could be jammed or slowed down by someone standing on it, depending on the strength of the motor.
another great feature (which quazi proved shouldn't be too difficult in the other IK thread) would be to give bones targets. (move joint toward x,y) for instance - if you wanted a character to grab for a moving object whether they could reach it or not. if they grabbed it and the moving object had enough momentum it could pull them off their feet, like a character grabbing a train moving by and being dragged by it. this could also be used to control head movement to follow objects. to aim a gun being held by a character with two joints for each arm, etc.
so yes, if bones and bone animation and IK were integrated into physics, it'd be possible to create animations that have a certain strength and attempt to complete at the mercy of outside forces.
also, an example of springy hinges would be a diving board, or a tree limb that would spring back into place after it was moved (2 or 3 springy joints). you would be able to set torque force, spring force, and damping force, to create everything from mousetraps, to long grassblades, or hair. the bones/hinges whether sprung or not should be able to be affected by gravity. I understand it might be possible to create those things now, but the difference in look and feel for a treelimb or hair that is affected by physics is night and day.