It is normal for your appliances to give off some heat during operation. For instance, game systems, TVs and computers may be warm to the touch while in use. The outlet, on the other hand, should stay cool. If you feel heat coming off the outlet itself, you need to find out why right away. Before you do anything, unplug the appliances from the outlet.
Do not plug anything back into that specific outlet until you diagnose the problem and have an electrician fix it. Treat switch cover plates the same as any outlet. The difference is with dimmer switches. These switches tend to increase in temperature slightly because they dissipate excess electrical energy. Still, these switches should be warm, rather than hot.