Most people set their side view mirrors to partially show the rear quarter of their car. A few years back, I heard Tom and Ray Magliozzi of Car Talk counsel someone to try a different method. I have been using this technique ever since, and I am very happy with it. The wide setting method virtually eliminates rear quarter blind spots by moving the side mirrors out somewhat to reduce overlap with the rear view mirror. Here is a diagram (click for full size):
It is important to note that you don't move the mirrors out so far that you have no overlap at all. By having a little overlap, you continuity between your rear view and side views.
The downside to this method is that you can't automatically see what is immediately beside and to the rear of your car, which is even more of a problem for vehicles with poor rearward visibility such as trucks and SUVs. To see what is beside you, you need to lean forward and left or right a little, depending on which side you want to see. Overall, though, I find I am much more frequently interested in lane changing safely than in backing into a parking spot.
Cartalk has a detailed explanation here.