They work by offering enormous discounts on all kinds of goods and services. First you register (for free). By becoming a Cudo member, each morning they email you the details of a terrific deal in your city.If something catches your eye, simply pledge your interest. When enough Cudo members sign-on, the deal's activated, and the terrific experience and savings are yours. Some of the deals include spas, massages, holidays, hair treatments, pest control deals. You can save up to 90%
Another great site where you can find some hot deals is Buckscoop.
This is a comprehensive shopping and cashback community site which lists deals, contests, freebies and also has discount vouchers for even more savings. Save big on holidays, computer and electronics, health and beauty, wine and spirits...it goes on and on. Really worth a look.
There are loads of online discount bookstores. But worth noting is that Borders is going out of business and you can pick up some even more amazing deals right now.
There really is no need to pay full retail price for anything these days.