Three players enter a room and a red or blue hat is placed on each
person's head. The color of each hat is determined by a coin toss,
with the outcome of one coin toss having no effect on the others.
Each person can see the other players' hats but not his own.

No communication of any sort is allowed, except for an initial
strategy session before the game begins. Once they have had a
chance to look at the other hats, the players must simultaneously
guess the color of their own hats or pass. The group shares a
hypothetical $3 million prize if at least one player guesses
correctly and no players guess incorrectly. What strategy should they use to maximize their chances of success?

(From - http://www.princeton.edu/~sjmiller/riddles/riddles.html)

Strategy : First person will be asked stand in a line opposite of the other two if he finds the second and third persons hats to be of same color otherwise in the same line as of theirs.

After the hats were put on the third person can tell the color of his hat depending on the position of first person(if first person is in the opp. side third mans hat is same as second mans hat, otherwise oppsite of secondmans hat)