I have actually never yet found a woman who does not enjoy a bit of light bondage and spanking. Maybe it is just the company I keep... Seriously, though, I think it is a quite common fantasy and you have to be fairly sheltered to not know about it/be intrigued by it enough to try it once. The difficulty I have always had is the reverse - woman are more likely to want to be tied rather than tie. Possibly a little problem due to gender roles in childhood?

On an aside, I have been surprised by the number of women who seem to have rape and kidnap fantasies. A scary number. None of them want to be actually kidnapped or raped for real but they find the idea of it really hot and enjoy roleplaying it. It just goes to show that if you ask the question 'what are your fantasies?' be prepared for some wierd stuff. If you thought fisting was wierd you may find what she likes even more bizarre...