There are two obvious options here, one already cited above. You can do both of them if you are willing to change the plug on the end of the cord and the receptacle in the wall. Right angle plugs can be installed, so that the weight of the cord is directly down. This works well in most scenarios, but, in a high vibration environment, like an audio listening room, twist-lock plugs work very well. The best solution is to replace the receptacle with a twist-lock receptacle, and replace the plug at the end of the cord with a right angle twist-lock plug.
Caution: One thing that can go wrong when using twist-locks, assuming you install them right, is that you can't jerk the plug out of the wall if your equipment starts to go up in smoke.
