The best tool that I have ever found for a parent to teach their child about bullying is the book Quiet Voice, Loud Voice.
Nicely illustrated. Nice story. Good karate images if that's your thing, but it's not all consuming karate that would discourage other readers. Really it's a nice story about a young boy who gets bullies, and uses a three step de-escalatioin philosophy to deal with the bullies. A great teaching tool for instructors and parents alike.
See more here: http://www.quietvoiceloudvoice.com/
Buy it here: http://bookstore.xlibris.com/AdvancedSearch/Default.aspx?searchterm=Hemenez
If you buy a copy, go to the website and the author will sign it for you with a very special, encouraging, lasting message for your child.