I could be wrong, but I think the 5th picture down on this page:
http://www.discgolfreview.com/resources ... aney.shtml
is about where the hit happens.
I've found that I get the best snap when I maintain correct wrist and forearm orientation thoughout the throw, am able to get my elbow to follow the right line and follow through strongly in the same plane in which I threw. I also find that my best throws are when the snap isn't audable.
As far as the rest of my body, I sort of think of it like a Slinky. Imagine taking a Slinky, setting it on a table so it sits upright and holding the top so it doesn't move. Then, twist the bottom and once it's twisted, let go of the top. It will uncoil gradually from the table up. I think of my last step in my x-step the same way. I'll plant my foot a little bit twards the target, my knee will follow, my hips will follow after that and then my elbow and shoulders will whip around. It all has to happen quickly, though or the timing will be off.