There are certain types of light red wines that lend themselves particularly well to being slightly chilled when matched with food, especially with fish such as seared salmon and tuna. They include early drinking styles of Pinot Noir, Beaujolais, Beaujolais Nouveau and other wines made from the Gamay grape.
White wines get their structure from acidity; red wines rely on a combination of acidity and tannins for their substance. If you chill down a red wine, this exaggerates the tannins, gives the wine more structure, and makes it less expressive on the nose. Conversely, as a red wine warms up, the tannins become less apparent on the palate and the wine becomes more volatile.


While you would think that it is a good idea to warm reds up to make them more expressive on the nose, what actually happens is that as a red is overheated, the nose loses focus: there's quite a narrow window of temperatures where a wine shows well.
On a cold winter's evening, I often find red wines at room temperature are just too cold to be enjoyable. They are shy on the nose and harshly structured. In the summer, however, I'll often pop reds in the fridge for 15 minutes before opening, as at a room temperature of 25°C+ they can be unfocused. Some light reds, such as those from Beaujolais, often benefit from being chilled down much as you might do with an opulent white.
The serving temperature has a startling effect on the taste of a wine. While you don't have to get it accurate within a fraction of a degree, it's worth paying attention to. In general, watch out for serving red wines too warm; it's much easier to warm a wine up in the glass than it is to cool it down. You have probably heard that red wines should be served at room temperature, and you are partly right. However, the term 'room temperature' refers to rooms in Europe way back when, and they were around 15-18°C, not the 23°C we find in modern homes. The slightly colder temperature slows the evaporation of alcohol, thus improving the aroma, flavour, and making the wine smoother.