Armature based Shapekeys?

Anyone happen to know a way to set up armature based shapekeys? I’m wanting to create my own stylized rig like the Morpheus and Cookie Flex Rig so I can reuse it for animations, and one of them would be height. If I did a shapekey for character height then it would be off the armature. So I want to know a way I can have armature have something similiar to a shapekey.