There are no real money heads up games on PokerStars or Full Tilt except for Sit n Go games. The reason must be that the rakes don't kick in in small pots. Whatever the case, playing heads up poker with play money is very addicting because of the action. Playing against very aggressive players is very stressfull, and not fun, because of the necessity of going to the showdown with no hand. The benefit of playing heads up is when, in a full ring game, most of the table folds and there are just two to four players remaining.
