The way most drivers, and car makers, keep their side mirrors doesn't actually cover the blind spot outside the driver's vision. Car and Driver illustrates a car mirror setup that, once you get used to it, could prevent lane change freak-outs.
The auto magazine culls its mirror alignment diagram from a paper published in 1995 by the Society of Automotive Engineers (SAE). That paper suggested, basically, moving your side mirrors to point further out into adjacent lanes, a trick that can take some getting used to:
The paper advocates adjusting the mirrors so far outward that the viewing angle of the side mirrors just overlaps that of the cabin's rearview mirror. This can be disorienting for drivers used to seeing the flanks of their own car in the side mirrors. But when correctly positioned, the mirrors negate a car's blind spots. This obviates the need to glance over your shoulder to safely change lanes as well as the need for an expensive blind-spot warning system.
So the trick is to get the side mirrors aligned just outside what your rearview mirror covers, and rely on your own vision to cover the areas in your peripheral vision. Neat trick, but as the magazine (and their commenters) mention, you'll want to train yourself on a neighbourhood road before taking this setup out on the freeeway.
Check out the Car and Driver post for a full look and explanation of the SAE-approved side mirror setup. Got a better solution to your side mirror setup? Do tell in the comments. Thanks for the link, cipheroid!.
How To: Adjust Your Mirrors to Avoid Blind Spots [Car and Driver]