I just called Chase to cancel my UA MP Explorer card (opened 02/2012) with the hope of getting a retention offer. The senior specialist (read: retention department) tried to remind me of the great benefits of the card, to which I replied that I already get them as Silver through my travel. His offer was a $100 statement credit; I promptly accepted and thanked him.
Interesting note: he made a point of saying that this was not an annual fee waiver, but a statement credit, and that he was not allowed to call it a fee waiver as the fee was part of the card contract. He was allowed to confirm that my annual fee is $95 and the $100 credit does indeed cover this.