Reward Your Web Customers
It costs less to retain a customer than it does to acquire a new one. One way to reward your valued customers is to give them special access to premium services by setting up a members-only domain on your Web site. You can make your members-only domain password-protected, and membership can be based on the amount of previous purchases or any other qualifications you see fit.
Excerpted from Attracting & Rewarding Outstanding Employees