Potbellys -- buy a $25 gift card and get a coupon for a free sub.
I do this one every year. I work in DC where there's a Potbelly on every corner. I LOVE their sandwiches and would eat there normally anyway, why not get the free sub on top of it? I'll usually buy 3 of the $25 gift cards & then they'll be gone by May or June or so... Thanks for the reminder.