I think there are some other threads on this on here. I just can't see how most people make any money - unless the Groupon customers are REALLY wowed with your service. For many people Groupon is like a sport or hobby! I have lots of friends who take advantage of these offers, all of whom do it to see what they can get! Most do not have regular beauty treatments anyway, only treating themselves with a Groupon deal once in a while - but have no intention of going back. Two of them got Saks haircuts and colours the other week. They were really impressed - but would never go back there and pay full price.
As for mobiles I'd be interested to hear if anyone's done it. I'm mobile and just think that when you've factored in petrol, travel time etc you're losing even more money than just the treatment time/cost.
Having said that, maybe it's a good way to get your name out there, but I'd be interested to hear what repeat business everyone's got from it. x