I have found warm water to be a great way to quickly defrost meat and fish as opposed to just letting it sit outside the freezer, which is what my mom does.  But I wonder if there are any negative side effects to the method, as in, for example, compromised taste or compromised food safety.  I do understand that the water shouldn't be too hot as to avoid actually cooking the frozen food. 
I wanted to add a new answer here that the USDA did a study in 2011 about warming meats in warm/hot water. The article sums it up well but in short:  At the U.S.D.A. labs in Beltsville, Md., Janet S. Eastridge and Brian C. Bowker test-thawed more than 200 one-inch-thick beef strip loin steaks in three different groups: some in a refrigerator at 37 to 40 degrees Fahrenheit, some in a constantly circulating water bath at 68 degrees, and some in a water bath at 102 degrees. Air-thawing in the refrigerator took 18 to 20 hours, while the room-temperature water bath thawed the steaks in about 20 minutes, and the hot-summer-day bath in 11 minutes. These water-bath times are so short that any bacterial growth would remain within safe limits. ... So there’s no downside to quick-thawing steaks, chops, fillets and other relatively thin cuts in warm water right before cooking. Large roasts are a different story. They take long enough to thaw that there may be time for significant bacterial growth on their surfaces. Prompt cooking might well eliminate that problem, but until this has been studied, it’s safest to continue thawing roasts in the refrigerator or in water under 40 degrees.  Sources: A Hot-Water Bath for Thawing Meats Effect of Rapid Thawing on the Meat Quality Attributes of USDA Select Beef Strip Loin Steaks) 