Publishers and bookstores should pay attention to the explosive growth of Groupon. Using the group coupon service online, one bookstore found 504 new customers this summer–each paying $10 for a $20 coupon for books, drinks, or sandwiches.

Watermark Books and Cafe, a bookstore in Kansas, used Groupon to create a special deal. In June, they promoted the “pay $10 for a $20 coupon” offer on Groupon–banking on the idea that at least 10 customers would take advantage of the deal. Hundreds of other customers ended up taking advantage of the Groupon offer. Read this retail case study to find out how it works. Maybe publishers could cut unique coupon deals for bestselling books as well?

Here’s more about the Watermark Books deal: “Though an online book glows in the dark, it can’t be shredded to make a papier-mache wig or taped to a shoe to replace an ice skate. Peruse useful reading material with today’s Groupon: for $10, you get $20 worth of books, drinks, and sandwiches at Watermark Books and Cafe on Douglas Avenue. This Groupon is valid for in-store purchases only and is not valid toward magazines, newspapers, or gift cards.”