Where can I trade BTC/USD with a small transaction fee? I don't need a leveraged account. I just want to trade with real money.

The Mt. Gox transaction fee is 0.60%. Is there a place with a lower transaction fee?
Base fees:


Mt. Gox: 0.6%
Bitstamp: 0.5%
Intersango: 0.65%
Bitcoin-Central: 0.498%