It always seemed strange to me that the coupons were essentially "get a $30 gift card for $15, to use whenever", when it seems like a lot of the deals could actually be good for both parties if structured more rigidly.
For example, selling a $5 cinema pass for a specific day, time, and show. So they book the whole screening room, sell exactly as many passes as there are seats, pack the house, and hand you your popcorn on the way in. Similarly with restaurants, where the whole venue could be booked out, and there's only two meals available (kind of like Summerlicious).
You're definitely not getting the regular-experience-but-cheaper doing that, so there's maybe a better chance of converting to try it out after the coupon, but even if you're only ever going to do it on the coupon, you can do it over and over again if it's good for both parties. If Groupon's marketing muscle can pack the house with cheapskates a few Tuesday nights per month, that's probably an all-around win.