Apostrophes

Not to start anything, because I know people feel quite strongly about their punctuation, but as we were setting up an account for the Kids Department on this here blog, we ran into a snafu that we often encounter. Somehow, the question is never settled, even when we finally make signage and someone gives a thorough explanation: Is it Kids' Books or Kids Books? We know it's not Kid's Books, even though that unfortunate possessive occasionally sneaks onto signage. But of the other two, we decided to go with Kids Books on our giant sign and whatever flyers we produce. As in, these are books for kids, not books that belong to kids. That official decision, however, hasn't stopped us from having the same plural v. possessive conversation every time we have to do something (like make our name for this blog).