Sarah Dessen is another of my favorite current YA writers. She's written around seven books, and they have some similarities: a smart and slightly misfitty teen heroine, family/social/school issues, and lots of personal growth. They often involve summer jobs and cute mysterious boys as well. They deal with big "issues" but are generally good at not falling into the "issue book" trap. They're all good, but This Lullaby is my favorite. The language is beautiful, the character is likable, and, well, it has the best of the cute mysterious boys.
I think That Summer is my favorite. This Lullaby was just ok. I moslty thought the main character was a twit, so I had trouble really liking the story. I've only read these two, so things could easily change when I read more.