Here's one that was emailed to me from Jake:
You try your last close and get up to go. As you close the door behind you, you stop, and come back in and explain you are new to sales. Ask what you could have done differently, what would have made them buy. Whatever they say, concede if you can. It's tough to tell someone no when they just told you they would buy from you if you did "this" and then you do it.