And most people don't know how to use them right, but i'll let you in on the secret:
Don't stir the whole pot! If you get the wort spinning, the steam bubbles build up under the surface and pop up all at once risking a quick ugly boil-over. Instead, use the tip of the paddle, you know, the part with all the holes in it, and whip it back and forth quickly through the foam only. This breaks up all the bubbles and gets you through the hot break time much more quickly than turning the heat down and blowing on it for 20 minutes
If you're talking about hot break, I do as other's do and spoon some off as I'm starting the boil. Then I don't worry about the rest.
If you're talking about just general foaming over when you're boiling, boil a little less vigorously and/or get some fermcap. It's great stuff! A few drops and the foam goes right down.