There's two I've heard mentioned a number of times.
"The Bighead" by Arthur Lee is supposed to be gruesome. Monster goring and raping a village, in explicit details.
and "Duet for the Devil" by T. Winter-Damon and Randy Chandler.
You can find excerpts from the former on amazon. The latter's supposed to be absolutely ridiculous, since he never relents. I couldn't find any excerpts for you though. I did find a foreword to Duet on the publisher's website, which discusses a lot of history of this sort of fiction etc, and will probably be an excellent source for you to look for ideas:
http://www.necropublications.com/titles/duetpreface.htm
Shame you're not Norwegian, or I'd post the story I wrote in 8th grade* Norwegian, which apparently was discussed for months in the teacher's lounge as an example of how horrible today's youth are. They blamed video - despite me never having seen nor read anything like it in my life. At that point anyways, for some reason I was excited about that sort of thing a few years later and watched a lot of absolutely terrible movies, simply because they were full of tasteless gore.
Oh, so I had a twisted sense of humor, but dammit, more school stories need unapologetic splattergore.
For some reason I never bothered to explore books that go into that sort of thing, but I suppose video was simply more visceral for me at that time. Nowadays I have zero interest in that kinda thing, oddly enough. I'd hate to think it's because I've grown up, but there we are.
*Ok, not really a shame, it's pretty damn badly written, heh. But hey, it does include someone being strangled with his own intestines and a zombie snacking on brains and vomit.