I was glad to see the medicinal use of culinary sage mentioned, but I'd like to offer an alternative method:

Take whole leaves of sage and steep for ten minutes in water just boiled. Yes, it is a strong-tasting beverage but with the addition of a spoonful of honey it's right tasty, and it's an excellent remedy for the winter congestion we can get, colds, bronchial and sinus congestion, etc.

Traditionally sage was said to give strength and this tea is a real tonic and strengthener of the immune system. I don't use sage leaves in cooking a whole lot but I always like to have a healthy patch growing so I can have some for those winter teas. It's a beautiful plant, too.