I work in the retail furniture/appliance/home electronics business.
We deal with MAP and UMRP all the time.
MAP (Minimum Advertised Price) doesn't prohibit me from selling for less, just for advertising a price lower than MAP. As Kyoshi stated, there are some instances where MAP is below my cost (some plasma TVs, for example).
UMRP (Unilateral Minimum Retail Price) is less common, but still used. Tempurpedic mattresses are sold at UMRP. You'll pay the same price no matter where you buy. Until not too long ago, high-end Maytag laundry was the same way. There are others.
Both systems are designed to help retailers maintain profit margins. Since I get paid by a retailer, I'm not one to object too loudly...
I used to work selling computers/networks. That industry has shot itself in the foot when it comes to margins on hardware. When you buy a $799 laptop at Staples/Best Buy/Wal-Mart, the retailer might be lucky enough to make $75 on the sale. It's no wonder they practically shove the extended warranty down your throat. They make another $75 on the $99 warranty.
I believe that most of the firearms industry has done the same thing. Somewhere along the line, selling firearms became a game of chicken: how low will you go? Of course, retailers like K-Mart and Wal-Mart drove the prices down then abandoned the market. Now it's places like Sportsman's Warehouse and Gander Mtn. that are keeping prices low.
I could go on and on...