Obama: < $30,000, 62% to 35%You're welcome to do the breakdown by race and gender if you insist, but this is much simpler: Obama won with folks who make less than the national average. Romney won with folks who make more.
Obama: $30,000 to $49,999, 56% to 42%.
Romney : $50,000 to $99,999, 52% to 46%
Romney: $100,000 to $199,999, 54% to 44%
Romney: > $200,000 or more, 54% to 44%.
ETA: For these numbers and more, see Groups Obama Won, Groups Romney Won - Interactive Feature - NYTimes.com. (Thx, Brian Holt Hawthorne!)