After creating multiple actions, each of which contains the channels only of specific bones of a rig, I find that I want a way to instantly select all the related bones of whatever action I'm working with currently. Mainly because I tend to have a lot of such bones per action, and also because I don't have a picker panel for the rig. So this would be a good alternative option, I am thinking. I would simply hit whatever button, and all of the bones controlled by the currently active action would be instantly selected, and ready to receive keyframes. That would be really neat-o.