I would suggest you be a good skeptic and answer the question about Santa Claus the same way you answered the question about Jesus: that you don't believe in him. Note this isn't the same as saying he doesn't exist, as this would be stating as fact that which is only highly probable.
The problem is that I'm already complicit in the deception. Besides putting quarters under her pillow, last night (Dec 24) I helped her mother put presents from Santa under the tree. Even before then, I was with her mother while she bought presents that were going to be (and eventually were) from Santa, and I knew all about it.
If somebody were fooling her about Jesus in this way, I would be a lot more worried. (I'm not sure how I'd intervene, which would depend a lot on circumstances, but I'd certainly want to.) But she'll find out about Santa soon eno...
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.