Look for shoes in the "neutral" or "cushioned" category (the two are basically the same thing). A couple examples - Asics Gel Cumulus or Nimbus. A lot of "minimalist shoes" fall into this category, such as the Saucony Kinvara and the Brooks "PureProject" series, such as the PureFlow. But the main thing is to find a shoe that feels good on your feet. Size up one-half to a full size from your street shoe to allow for foot expansion when you run.
First, make sure you're really an underpronator, or supinator. Many runners think they're supinating because of the wear on the outside corner of the shoe's heel. This is a high-abrasion spot because it's the first contact area for heel-strikers. Where is the most wear in the forefoot? Is it also on the outer side of the shoe? Is it well-centered? Or is it under the ball of the foot? If the forefoot area of your shoe shows the most wear on the outer edge or it's well-centered, shoes in the neutral category are best for you. If you're wearing the inside edge of the forefoot, under the ball of your foot, you're overpronating and need shoes from the stability category. If in doubt, go to a specialty running shop, where experienced runners can do an analysis for you and make some recommendations that also take into account your arch height and general shape of your feet.
I am a PT and I have been treating individuals with foot issues for 10 years. The reason there is so much information for "overpronators" is because >90% of people over pronate. Truly neutral and/or underpronators (high arches) are rare. The first posts answer was pretty spot on in reference to neutral shoes or cushioned shoes and possibly going a bit larger on the size as you want to allow the foot to pronate as much as you can to allow the mechanical forces of the foot to propel you forward (not allowing pronation would lead to a number of issues including stress fractures- i.e. avoid rigid orthotics that restrict pronation regardless of who made them and stretch the foot for a few minutes prior to running).
The second post is very interesting. I completely agree with having your gait checked and I would agree that proper shoewear is good for those with back issues (or knee or hip or...). I am not a proponent of going to a shoe store and having them "analyze" your gait. Why:
1) Who is analyzing it- Few have the skill or knowlege to judge the disfunction and they rarely work at sporting good or shoe stores.
2) Videotaping on a Treadmill- No way they can really tell you what is going on using this information and diagnosing "high arches" because you are "coming down on the heels hard..." makes no sense. In fact, people who "run like a duck" typically are very heavy overpronators unless they have some severe knee or hip issues. Distribution of forces occur in mid-stance and not at initial contact of the heel. Pronators hit mid-stance position too early and overpronators have difficulty achieving mid-stance leading to a push off on a rigid foot. The whole issue boils down to the laxity or ridgity in a ligament that runs from your heel to you middle foot that prevents your ankle bone from sliding to the floor. It's formed as we are young and has a hard time adjusting to our changes in weight bearing (weight, activity, injury/condition). Pregnant or post-child birth women are at risk of further pronation due to the hormones causing generalized laxity. I always recommended good arch supports during pregnancy and for the short period after until the hormone levels equal out. This would help with the increase in shoe size and width that many women report after having kids. The fact is that a skilled individual can easily assess an overpronator or underpronator by observing the feet statically and then with walking (and/or running/jogging) to determine what shoes you need. Shoe companys fix the issue by wedging the inside heel at different levels. I personally believe this is cheating mechanically, but it works (for the most part).
3) They are Salesman- Whether they know a little or a lot, the salesman will always push you toward a more expensive shoe and/or insert. Typically, the inserts are irrelevant if the shoes are good in the first place. It's like selling you the extended warrenty. Why would you purchase a neutral shoe and then add an supportive insert? It makes little sense. I warn my patients to never trust shoe salesman, unless they offer a 30 day trial policy with return/replacement. Any good/reputable place would do this. Not working on commision would help as well, but this is pretty rare.