First, I would give them to people who are browsing garage sales or flea markets. They are obviously looking for some bargains, and because Tripleclicks advertises to be the largest online garage sale, these might be some great people to approach.
Second, you could try leaving some in shopping malls, like at the food court where lots of people congregate. YOu never know if one of these people might be looking for an online store to shop at, and this would be a great incentive.