Here is an obvious, but very concise, way of analyzing debates, or almost any political phenomenon: TAG CLOUDS!
What interested me was the focus of Clinton and Edwards. Both had just a few main concepts, and they were VERY different.
And you can really see the effects of either strategy or personality. Wonkiphonetics don't play very well. Candidates need to be Hemingway, not Faulkner. Look at the word totals for the debate:
1,872 - Senator Obama
1,766 - Senator Clinton
1,518 - Senator Edwards
1,281 - Governor Richardson
1,180 - Representative Kucinich
961 - Senator Biden
912 - Senator Dodd
753 - Senator Gravel
I actually Biden talked more than that, but maybe it's because he is like fingernails on a blackboard to me.
(Nod to TK-S, who knows stuff)