Just finished working on this biped rig. Admittedly I learned it from the brilliant folks at pluralsight.com, but this is the version I developed from their lead. Hope it benefits you on your next project, as we all know setting up a rig can be an "experience".
Note: It even comes with a few Xpresso controls in the fingers and feet (mesh model not included).
_l_ = Left side
_r_ = right side
sc = Master controllers
bn = Bones you want to add to your skin deformer
If you want to know how it works, or how to build your own, please check out the tutorial by Delano Athias, it'll blow your mind: