Crème Fraiche
Crème Fraiche is a slightly soured cream, thinner and more subtle than sour cream, but with more fat. Unlike sour cream, crème fraiche can be whipped, and it can be heated without fear of curdling. It is a French product originally, but it is made all over Europe and in some parts of the United States.
You can make homemade crème fraiche by adding a small amount of buttermilk or sour cream to heavy cream, and leaving it at room temperature for several hours, until it thickens.