Having just returned from 2 weeks in Cala Bona, where we enjoyed the cocktails at the Hotel Cala Bona, and were told about a discount scheme which they run. Apparently the scheme has run for a few years, and yet some regular visitors were not aware.
How it works - you pay your bar bill and keep the receipts. When you have collected E30 worth of receipts, you take them into reception where there is a touchscreen monitor and a scanner [don't worry as reception helped us to do it]. You follow the instructions on the screen, and scan the bar code on the receipts. When you have scanned a minimum of E30, you push a button and a voucher for E3 is printed, which you can use off your next purchase.
You do not need to be a resident at the Hotel to take advantage of this.