When the steak is ready to be removes from the skillet place it on a plate and gently cover with a piece of aluminum foil. Note the time. In five minutes you (or whoever is eating this steak) should be ready to have the best steak of their lives. This five minutes of resting lets the juices in the steak even out, and the steak relax so it will be as tender as warm butter.
You still have a few options at this point. If you want throw some chopped shallots, a cup of red wine, a tablespoon of Dijon mustard in that cast iron skillet and make up a sauce to pour over the steak. This is an incredible sauce that really should not be over looked.