Only buy games that have good online multiplayer.
I refuse to pay the $60 price tag on most games, as they just are not worth it. Most just don't have the replay value and I'm looking harder at every dollar I spend these days.
I pretty much rent everything from gamefly and get to stay on top of games that way. Just wouldn't be possible if I bought every game I want to play for $60. If the games is REALLY GOOD i'll buy it, otherwise back it goes. Last game I did purchased was Bioshock and probably rented 30 games since then.