Gubar: ta..... I have tried it before but I didn't really notice it make any real difference. I'll give it another go.

Steve: I love it.
I see in your base mesh you have extruded down for those dips at the base of the neck... I did that on a model recently and it worked really well.
I like the topology of your torso area particularly the pecs and the flow out to the shoulders looks like it would produce really nice, natural arm movement. And the concentric topology of the six pack area growing from the middle out and then wrapping up and round the back.
Did you model that as is pre-sculpt, or have you re-topo'd to achieve that?