Apparently some animals (eg walrus) have areas of skin that are especially adapted for cooling, where the blood vessels are close to the surface. They are able to control the blood flow to these "thermal windows" and fine tune their temperature.
Humans lose more heat from areas where more and larger blood vessels run close to the surface, including the arm pits, knee pits, wrists, neck and face. If you are hot and flushed you may be able to see where the "thermal windows" are trying too dump heat.
For some great Infra Red images go to WorldofWarmth by clicking here.