The homepage of the Office of Juvenile Justice and Delinquency Prevention's Statistical Briefing Book "provides basic information on juvenile crime and victimization."
The Yahoo! Directory on juvenile crime is another approach to researching this subject. There, you'll find the subject arranged into issues such as the death penalty, school violence, and teen court.
The Washington Post offers a "Juvenile Violence Time Line," covering acts of violence in the U.S. from 1996 to 2000.
Let's say you'd like to see if an aspect of the Columbine massacre would be suitable as a research topic. This CNN special report called "Are U.S. Schools Safe?" will give you information that will help you decide.