So, apparently only 27 states have legally required their electors (the members of the Electoral College) to vote for their states candidate. Wikipedia has a good list of faithless electors. Not that any of these have ever switched the election, but it's interesting none the less . . .
Nebraska and Maine are the two states where it's not winner takes all - in both states two votes go to the statewide winner, while the rest go by winners in congressional districts. Apparently Colorado had an issue this year to switch to proportional representation.
Sorry for the lack of citations for these last couple entries . . . so many sites, and random trivia, and I'm tired . . .