Zeth Willie provides a uick tip for modeling with better edge flow in the shoulder area of a character providing better deformation results when incorporated in a rig.

A quick(-ish) vid about how I sometimes create more anatomically correct edgeflow in the shoulder area of a model

Zeth notes that this technique was based on a Bay Raitt modeling time-lapse, where he makes an adjustment to the extrusion from the torso for a more natural angle before extruding the rest of the arm. Zeth also has a lot more information on this on his blog, check out the post for Maya/Rigging/Modeling: Tip for creating better shoulder edgeflow here.