The Geography Club by Brent Hartinger
Russel knows what it's like to be different: he's convinced that he's the only gay kid at his high school. He also knows that he doesn't dare tell anyone else--if anyone found out the truth about him, Russel is sure that he would be ostracized and tormented by the other kids.
One night, while searching for kindred souls on the Internet, Russel chats with another gay kid from his town--in fact, this kid attends his school. Discovering the truth about Kevin leads to even more revelations: there are other gay kids in the school who are lurking below the "student body radar." The gathering of this group eventually leads to the formation of a student club, which they name "The Geography Club" in order to dissuade others from joining. After all, what could be more boring than a geography club?
This is not just a book about gay kids and straight kids. This book is about being different, and being afraid to be different. One of the best characters in the story isn't even homosexual--he's just an outcast, poorly-dressed, unconventional nerd. There is no tidy ending, and not everyone emerges from his or her personal closet, but each character does grow and change in the course of the book. And that is what makes a really good book. No strong language or graphic descriptions, but some sexual situations.
For ages 14 and up.