I do the daily, and if I have been there for a longer period with the same mousekeeper, or someone gave me extra special service, I try and do something extra.
Last time it was finding out the person's name by calling her manager and describing her in detail, and then leaving her a large tip in a handmade Christmas card. I've also left things like Target gift cards in past for something extra special. (Once at POR I received a birthday gift early from my friend, and left the gift bag in the room. The mousekeeper must have seen the 'happy birthday' on the bag, because when I came back there was a birthday card to me from all the characters!)
Last time it was finding out the person's name by calling her manager and describing her in detail, and then leaving her a large tip in a handmade Christmas card. I've also left things like Target gift cards in past for something extra special. (Once at POR I received a birthday gift early from my friend, and left the gift bag in the room. The mousekeeper must have seen the 'happy birthday' on the bag, because when I came back there was a birthday card to me from all the characters!)

I seem to remember that on an episode of Big Brother when one of the houseguests made another mad. 