The United States CERT (Computer Emergency Response Team) has an article up about cyberbullying. If you've been in a chat room, you've no doubt seen someone engaging in this type of behavior.
Cyberbullying refers to the new, and growing, practice of using technology to harass, or bully, someone else. Bullies used to be restricted to methods such as physical intimidation, postal mail, or the telephone. Now, developments in electronic media offer forums such as email, instant messaging, web pages, and digital photos to add to the arsenal. Computers, cell phones, and PDAs are new tools that can be applied to an old practice.