I teach and these are great to use as name plates for the front of the desk. The magnets have so much stick to them that I can generally use them more than one year. I can pull off the old business card and there is enough sticky tack left for a new one to adhere to it. If it does not pull of easily the magnets are strong enough to allow a person to past a new card directly on the old one.
As a teacher I look for shortcuts and this is one. My students each have a magnet which they move to tell me if they are buying or carrying lunch. They work GREAT!!!!
Most of the time I use them to make favors. I helps that I don't have to cut them but sometimes the paper is so hard to remove and they aren't as sturdy as they used to be.