Got my hands on a copy of Dr Melissa Kang & Yumi Stynes' Welcome to Sex from the library and I'm embarrassed at how informative I'm finding it. Many things I had a vague idea about, but nothing so concrete as a drawing on the page (female condoms, anyone?)
Some sections seemed a bit too female-centric for a book aimed at all teens (e.g., on relationships), but I suppose there's only so much a single book can cover!