book talk: appropriateness???

So, in further full-nerd disclosure, I have to update you on this series that Jake and I are reading together. We are half-way through the third book, and thoroughly sucked in, loving every minute of it.The series combines really well-developed characters with the kind of adventure/fantasy that makes me love The Lord of the Rings series.

However, as we were reading the other night, I started to wonder...how appropriate are these books for kids? Jake and I sometimes talk about our hypothetical children (a term my friend, Crys, thinks is hilarious!), things we want to share with "them" from our childhood, and among the stuff I want to share is more than a few books. Maybe even these books.

But when? 

When is it ok, for example, for a kid to read a sex scene? Or a really violent battle scene? Or swear words?

I ask these questions, because it is something my parents thought about with me--precocious twelve-year-old that I was, I picked up the Odyssey along with this book about Greek mythology--and had to have some interesting conversations with mom and dad as a result.

What about you? Were you ever not allowed to read certain books because of their content? Would you allow/not allow your kids (real or hypothetical) to read certain books?