Choosing Age-Appropriate Media for Children

This week, a fifth-grade teacher asked me, how can I reliably know if a certain book that I haven’t read myself is age-appropriate for one of my students?  (In this case, it was the final book in the Harry Potter series.)
Not having read that one myself (I only made it through #5!), I posed the question to a children’s librarian friend who, in turn, referred me to the website, Common Sense Media:
Common Sense Media is a free, non-profit, non-partisan website that uses information on child development to review movies, TV shows, books, games, web sites, and music for children, their parents and their teachers.  It also appears to contain a wealth of parent and educator information on the media and media safety.
They do ask you to sign in, but it’s free.  I was able to see a good deal of content without signing in, but the site was easier to navigate after signing in, and they have a good privacy policy.
Not only do they rate these media forms for age-appropriate-ness, they also address the question, “Is it any good?” which I loved!  We all know that some things kids would like to take a look at might be age appropriate, but also might not be worth their time…
It then rates the media (be it a book, website, etc), based on “The Good Stuff” it contains(messages it sends, role models, illustrations), as well as incidences of:
“Things to Watch Out For” (violence, sex, language, consumerism, drinking, drugs, & smoking).
It also recommends topics that the media form in question brings up that adults may want to talk about with their children/students.  It allows for reviews by users of the book, movie, site, game, etc., as well.
I found this site valuable, as a parent, and as an educator!
PS (March, 2013): Common Sense Media is now available as an app!  It can be found by searching for Common Sense Media, or by searching for “Kids Media.”