Product review (5 stars): Look nice and cover up those unused burners
1.  Look very nice
2.  Keeps unused burners clean, especially if you cook something that splatters from the other burners you are using.
3.  Beware if you turn on the wrong burner and cook underneath these covers!  I took the burner control knobs off my stove for the back burners that had these covers on them to stop me from inadvertently turning on the burners while these covers were on them.  Twice I scorched other burner covers by mistakenly turning on the wrong burner.  Duh.