Whole house fan

Graingers catalog and .com has a big selection. A whole-house fan is a simple way to exchange inside air for outside air. Here's why so few people do it; Only occasionally is the outside air more desirable than the inside air. Heat, Humidity, Dirt and Pollens are outside. Think how dirty your patio furniture or your car gets in two days outside. 5 A.M., when the air is usually calm and cool is supposed to be the worst time for pollens. A fan won't cost too much, and the air circulation will feel great. Insulating the large roof makes a vast difference in the livability of an Eichler. Nothing else comes close to making an Eichler a better place to live. Unfortunately, any roof is expensive, and only considered when the old roof is making life miserable.

The original owner of our Courtyard model installed a fan on the side of the garage; it is about 36" in diameter and during last summer, we used it to exchange the air in the BR area. Our 3 small BR's sit behind the garage and have no natural outside shade, and the sun cooks the area from mid-afternoon to sundown. Our MBR can cool off by opening the patio door.
I don't have any specific ideas about the type of fan, but here are my thoughts.
(1) Clearly you need enough horsepower to move a large quantity of air, and I think this is measured by cfm (cubic feet per minute).
(2) Where are you placing it?? In our case, the fan in the garage (not our decision) moves some air out through leaving the entry door ajar. As the previous posting suggested, it only makes sense when outdoor temperature is lower than indoor, which is always the case in the evening. Thus, we tolerate no cooling during the daytime, but need to cool the BR's in the evening and a fan seems to be least expensive and mostly "green."
Wherever you place it will impose 2 contraints: size and noise. The place you want to install a fan may only accomodate a particular size. Even if size is not an issue, a powerful fan will inevitably be more noisy. Bathroom fans can be quiet, but I doubt they can move the volume of air you need. If you can find a house fan by Panasonic, it would be a good bet - - the Japanese companies seem to factor in "comfort" & livability in their products.
The noise factor in the evening can be fatiguing for you and your neighbors - - our neighbor facing our garage fan tolerates it.
One obvious place is through the roof, but it creates a host of other potential problems.
(3) The thing I noticed is that if you isolate the space that you want to cool, the air exchange rate will be faster (like closing your mouth at the dentist when siliva is suctioned out). Thus, if you can close off half the house (i.e., close a door separating the living from sleeping area), the pressure is more concentrated and the air flow out-and-in should be faster for a given size fan.
What are you plans??

Typically, a whole house fan system is used in homes in the central valley (I've installed about 7 in Davis and Sacramento area); where there are many 90 degree+ days during the summer months. A whole house fan is generally installed in conjunction with an attic fan. The attic fan is usually connected to a thermostatic switch (set to go off a specific temperature).
When the attic heats up (and trust me they get very hot) the attic fan turns on, and if the CFM rating on the fan is correct, will eject the 100+ degree heat to the outside.
The whole house fan is a fairly large (about 2'-3' square) unit that mounts in between ceiling rafters (usually in a hallway near bedrooms), has a few speed settings on a wall switch, and is operated, either manually or thermostatically, (in any location inside; I usually put them near the fan on the wall), and it functions to draw the hot air upwards into the attic (which is usually insulated from the rest of the house), which then is ejected outside by the attic fan. This system is popular because:
A. The entire system (fans, switches and misc. electrical materials) usually costs less that $350.00 (plus installation, takes a few hours)
B. The operating cost is a fraction of the cost of A/C
C. It is effective at reducing the interior temperature about 10-15 degrees.

When installed properly, dampener opens, and it draws the hottest air (near the ceiling) in your house up and out, and it really does work. (It does not necessarily have to exchange the outside air, it simply takes the hottest air out of the house) I've only installed one of these systems in the Peninsula; mostly because I honestly have not yet thought to design a practical way of installing one in the T & G (tongue and groove) roof decking, and I'm not so sure that the fan would work so well ejecting it directly out side without collecting it first into an insulated space (such as an attic) rapidly.

Unfortunately, this is somewhat academic because Eichler homes do not have attics, (unless there was one added); If your home does have an attic, when properly installed this system can be a great inexpensive way to cool off a bit on those really hot days