This WSJ piece has a nifty little break-down chart on candidate preferences among different groups.
Among Democratic primary voters, it's interesting to see that John Edwards, who talks about the poor a lot, is least favored by the poor. (The poorer, the least likely they are to support him.) Hispanics are especially favorable to Hillary Clinton, and least inclined towards Obama. Blacks really dislike Edwards, (or are simply more pro-Hillary & pro-Obama) giving him just 2%.
On the Republican side, Huckabee isn't getting as much of a gender gap as I'd thought, only 1% difference. The big gender gap is women liking Giuliani much more than men. That is a bit surprising to me.
I also looked at how predictable my own potential choices (McCain and Romney, although I have deep misgivings about both) are by various statistical measures. They finished 1st & 5th in my region and my gender. 3rd and 4th with respect to age group & occupation. 1st & 6th with respect to area type (suburban, urban, rural). 2nd and 5th with respect to news source (internet, blogs).