is this what drove the kids to go on crazy sprees and go bananas on you me and dupree?

Starter of Controversy.

Onani Master Kurosawa it's a good example, not right away but eventually

ichi the killer

Quote from britnh3

this has some element of it but it's seriously creepy...definitely mature...
Wolf Guy - Ookami no Monshou

there's a scene where a guy goes nuts and kills everyone who "bullied" him and his brother

He was really the bully though... just one that had inadequacy.

[color=green]"Officially, this machine doesn't exist, you didn't get it from me,
and I don't know you. Make sure it doesn't leave the building."[/color]

Higanbana no Saku Yoru ni only 3 chapters though..but it's definitely creppy...and twisted)

Gantz has what you're looking for in a couple of the characters - one that shows up early in the series and one that shows up later -

they both kill everyone that tormented them.

pika ichi

best shonen manga couples :

shinichi X ran
natsu X erza
ippo X kumi
naruto X gaara

Hahaha, you should totally watch "Let the Right One In." It's a movie though.

Elfen Lied Though the bullies got they deserved

What a blood bath.

Jigoku Shoujo is the perfect manga for stories about getting even with those that do you or your loved ones harm. What could be more justifying then sending them to hell.

It may not fit the bullied bit - unless your counting parental abuse - but one rather perky character of Mirai Nikki gets pretty creepy and twisted. Not to say the rest isn't >_>

Second Ichi The Killer ... kinda

The beginning of Junk - Record of the Last Hero is also like this.

The main dude hasn't been in school for like one year. Then he got a powersuit and one of the first things he does is getting revenge on the bullies that made him stay away.