My family and I have been making use of this service (K-Shop radio shopping show) for over 20 years.
Here is how it works- they go to local (and sometimes out of town) merchants and arrange to market their services. Then they create their certificates. Their certificates are usually at least 40% off of the normal cost for whatever products/services you are getting, and sometimes closer to 80%. Then we (the consumer) go on their website or call into their show during their radio hours and order the certificates we want. And then we go shopping :)
They have normal stuff like haircuts, oil changes, restaurants. And then they have unusual things too, like paintball, shows in the casinos, and wedding photography.
Some of the more interesting ones that I've gotten over the years were Running With the Bulls when that happened in Mesquite and the sunset on the Strip helicopter tour.