If you like The Truth About Forever by Sarah Dessen

What My Mother Doesn't Know by Sonya Sones.

Sophie's mother doesn't know about the boy who's pressing Sophie to go further than she wants. Or about the boy she chats with online. These sharp, funny, and tragic poems tell of Sophie's sometimes painful but always passionate journey of self-discovery.

The Sisterhood of the Traveling Pants by Ann Brashares.
During their first summer apart, four teenage girls, best friends since earliest childhood, stay in touch through a shared pair of second-hand jeans that magically adapts to each of their figures and affects their attitudes to their different summer experiences. As you may know, this is the first of a series - the others (in order) are : The Second Summer of the Sisterhood, Girls in Pants, and Forever in Blue (coming out in January 2007).

The Boyfriend List by E. Lockhart.
A Seattle fifteen-year-old explains some of the reasons for her recent panic attacks, including breaking up with her boyfriend, losing all her girlfriends, tensions between her performance-artist mother and her father, and more. The sequel to this book just came out; it's called The Boy Book.

How I Live Now by Meg Rosoff.
To get away from her pregnant stepmother in New York City,
fifteen-year-old Daisy goes to England to stay with her aunt and
cousins, with whom she instantly bonds, but soon war breaks out and rips apart the family while devastating the land.

The True Meaning of Cleavage by Mariah Fredericks.
When Jess and Sari, best friends since seventh grade, begin their
freshman year of high school and Sari becomes obsessed with a senior
boy, Jess wonders if their friendship will survive.

Twilight by Stephanie Meyer.
When seventeen-year-old Bella leaves Phoenix to live with her father in Forks, Washington, she meets an exquisitely handsome boy at school for whom she feels an overwhelming attraction and who she comes to realize is not wholly human. This book also has a sequel, titled New Moon.