hi,
I made a script starting from the Papasmurf armature/action baker one, with options dedicated to the BGE (keystep, frame offset, existing action updates, bone filters…) :
http://blenderartists.org/forum/showthread.php?t=189451
I use it once I’m done with the animation of a complex rig with a lot of constraints, and that I want to use the animations in a game :
the known idea is : less bones to animate + less constraints to solve = higher framerate in your game
. can create a simpler rig from the original one (no controlers, no ik, only ‘flesh’ bones are copied)
. can turn the original animations made with constraints like IK, shrink, copy etc… into a new animation with loc/rot/scale keys on the ‘flesh’ constrained bones.