I have a number of Loyalty cards - the one at my LQS if I spend over $100 you get a $25 discount on anything in the store and I've got one for Fabricland every day you get at least 25% discount on anything in the store and then they have weekends where you get 50% off quilting products. We have one for Panera Bread which we were in on the weekend and they told me we had earned a free lunch item.
I think if you shop at a place often enough its worth while getting the loyalty card. I've also got one for our bookstore similar to Amazon where every time you place an order you get 10-15% off your order, every little bit helps.