Vegan Virgin Valentine by Carolyn Mackler was a book I picked up this week and enjoyed. Mara Valentine is your stereotypical type-A overachiever. She's gotten into Yale (early admission), Johns Hopkins summer program (2 college courses, 1 summer), is fighting with her ex-boyfriend over valedictorian status (she's so going to win) and life is pretty much manageable until her 16-year-old niece (yes, niece) V moves in and wrecks everything, including Mara's identity.
I love books about overachievers losing it (see: The Overachievers, Hacking Harvard, my own novel) and this was no exception. I wouldn't recommend this for readers under 13 or 14, and I do have some stylistic problems with the book, but... if you (are a girl) looking for a light, funny read, I recommend Mackler. I believe the sequel to this book, Guyaholic, was released this past year: where V, the most memorable character, takes center stage.