If I'm too lazy to grate butter, but need it to be softened for a recipe, I turn to the oven for help. I have a gas stove and when the oven is on, the stovetop gets pretty hot, too. I place the wrapped butter sticks on the stove. The heat from the oven softens the butter in just a couple of minutes. Don't forget to rotate the butter, so it gets evenly softened on all sides. Voilà! Instant soft butter.
What's your trick for rapidly softening butter?