If you have never thought to yourself "this shouldn't be as hard as it is to quit" then you probably wouldn't be at this site. (!) The great thing is that it isn't as hard as it seems.
The first book I read about quitting porn I bought in 2007: The Porn Trap. I suggest you read this book, if you haven't already.
My assessment of it's effectiveness in helping you quit is pretty low but it does describe some techniques that could help you stay away for a little bit. Written in a faux clinical 12 step manner this book talks about the "symptoms" but not enough about the cure. Fortunately there are people like Marnia around who host sites so people can help each other find their *own* answers.
Has anyone else seen the British documentary following the progress of two chronic masturbators? Needless to say it's where I first learned the term "cock ache."
"I Can't Stop Masturbating" was filmed in 2007. YouTube is currently flagging part one of the doc saying it has "inappropriate content." (Even though any teenager can sneak up on their friends with a video camera and film him jerking off to Warcraft!.)
"95% of men admit to masturbating. But some men masturbate more than others. Much more... 'I Can't Stop Masturbating' will follow two men as they try to break an addiction that is destroying their lives."