What are some good teenage romance books?

Not twilight (I've already read that) but other books...i love books that the main character has something else going and happens to fall in love on accident....ex: Megan Meades Guide to the McGowan Boys, The Host, Life as we Knew It (the last book), Secrets of my Hollywood Life, The last book in the Percy Jackson Series, etc..... Oh and I have a nook so I hope these are available as a nookbook!