Just what can be done to stop bullying?

I always hear idealistic propositions for what can stop a bullying problem, but then we keep having stories where bullying is taken much too far. This question was inspired by a story I just read about a 13-year-old gay boy in Texas who committed suicide after being tormented by bullies in middle school because of his sexuality and religious views. http://www.queerty.com/shock-gay-texas-13-year-old-asher-brown-shoots-himself-in-the-head-after-horrific-school-torment-20100928/

In today’s age of “zero tolerance” policies on bullying, how can something like this be allowed to happen? How much is the parents’ responsibility? How have you seen bullying dealt with? How is it supposed to be stopped?

This story just really got to me and it really makes me want to do something about bullying in schools, particularly anti-LGBT bullying.