I expect your daughter to become a frightening young woman, and I mean that in the most complimentary fashion.
She's a cross between me and Arkady. She's frightening already. We worked out by the time she was about six months old that we would have to protect the world from her, not the other way around. My goal is to help her not become the next Dark Lord. I am, of course, enormously proud of her.
Teaching rationality of any sort to a three-year-old is of course quite difficult, but that she has no confusion between reality and story - and doesn't make up stories as excuses - is a pretty good start. Also, the Henson method - tell your kids ridiculous whoppers - is fun. And more fun because she gets that it's just play. When I'm supplying the voice for her toy dinosaur, it tells her things like "I'm not a dinosaur. I'm not here. I'm actually over there. Go, look, over there!" She is delighted by this sort of absurdity. I expect other children would as well, particularly in a safe environment such as playing.
Henson method? Quick Google didn't help (some artist?).
I've long entertained a dubious regard for the practice of lying to children about the existence of Santa Claus. Parents might claim that it serves to make children's lives more magical and exciting, but as a general rule, children are adequately equipped to create fantasies of their own without their parents' intervention. The two reasons I suspect rest at the bottom line are adherence to tradition, and finding it cute to see one's children believing ridiculous things.
Personally, I considered this to be a rather indecent way to treat one's own children, and have sometimes wondered whether a large proportion of conspiracy theorists owe their origins to the realization that practically all the adults in the country really are conspiring to deceive children for no tangible benefit. However, since I began frequenting this site, I've been exposed to the alternate viewpoint that this realization may be good for developing rationalists, because it provides children with the experience of discovering that they hold beliefs which are wrong and absurd, and that they must reject them.
So, how did the Santa deception affect you personally? How do you think your life might have been different without it? If your parents didn't do it to you, what are your impressions on the experience of not being lied to when most other children are?
Also, I promise to upvote anyone who links to an easy to register for community of conspiracy theorists where they would not be averse to being asked the same question.