As already mentioned to David, I thought I would post it up here anyway so he doesn't forget about it...
Bones need to have either:
(A) Joint constraints
(B) The ability to tell the bone which direction to rotate to the next keyframe.
This would help a lot with exaggerated animations in particular, where you find your characters "bits" bending around the wrong way to reach the designated keyframe position simply beause it's a shorter distance to move.