Whole house fans can be very, very noisy but they are incredible for cooling off your house the moment the sun drops. We opted not to do this as the only location for it would be in the hall by the bedrooms, sounds like a train.

what we DID do was put in a thermostatically controlled attic ventilation fan. It kicks on automatically when the attic space gets above a certain temp. It sucks in on one end of the attic, blows out the other. Our house is a good 15 degrees cooler now since we put this in.