Inside the cult of Groupon

Psychologically, sites like this hit us right where it counts, marketing experts say.

Limiting each deal to a single day, and counting down the hours and minutes left, prompts us to Act Now! Add in the specter of exclusivity, and the sites confer a little glow of specialness on recipients

Source:
http://www.bundle.com/article/Inside-the-cult-of-Groupon-11165