Here's an interesting factoid from Al Jazeera.

The next American president will be elected on January 6, 2013. On that day, the votes of 538 people - the members of the "Electoral College" - will be counted at a joint session of the United States Congress (the name of the US legislature).

Provided Barack Obama or Mitt Romney receives a majority (that is, at least 270) of these votes, he will be re-elected/elected president of the United States.

Only 538 people actually vote directly for the President - and Vice-President - of the United States. When everyone else votes on November 6, they are merely playing a role in determining who these 538 "electors" are.