This tip is one that I have been using for health reasons, but is also a thrifty tip. Especially since the price of a pound of butter has about doubled recently.
Since I have to restrict saturated fat in my diet, and the transfats in margarine are not good either, I take one pound of butter, which has saturated fat, and mix it with a blender into an equal amount (2 cups) of light olive oil, which replaces half the saturated fat with healthier monounsaturated fat . It retains that good butter taste, and spreads easily cold from the fridge. All pluses in my book!