The service entices users with playful incentives to check in to locations--usually local businesses--using badges to indicate the frequency of visits and assigning "mayor" status to a site's top visitor in a given day. Using Foursquare can be simply fun, but it can also earn customers discounts and freebies.

In addition, the opportunity for without huge marketing budgets to sign up is especially compelling. Using Foursquare has these distinct advantages over other social networking marketing:

1. It Reaches Real Customers

Though it's easier to round up hundreds of followers or "Likes" on Twitter and Facebook, as compared to check-ins on Foursquare, only a tiny fraction of your Twitter and Facebook followers will convert to paying customers, while most everyone who checks into a location using Foursquare will make a purchase.

2. It's Hyper-local