Ive done the magnet business cards before with other work and made them myself as well. Really easy to do, the magnet is a pre-cut sticker that you just apply to the back of your cards. I've never really got feedback on those before, so thats why Im going to try the static cling reminder. Again, at only $0.50 each, its cheap and I think if even 20-30% of people keep them it will be worth it.