Japanese Horror Comics
 

I recommend Uzumaki for really disturbing and odd concepts and gore. It's about a small town cursed by spirals. VERY twisted and frightening imagery. They also made a movie of that one. And Pet Shop of Horrors which is slightly campier and more spooky than gross.
Also Parasite is pretty freaky and scary too.
I think Viz and Tokyo Pop put those trade paper backs out so you should be able to find them in bookstores and comic shops.

Haven't read the Uzumaki comic but liked the movie.

Junji Ito wrote that and also a great comic (and sequel) called Tomie. Tomie was made into a not-so-great film. He also wrote Flesh-colored horror, which is along the same lines as Tomie. All of them are worth tracking down.

I just found this, a FREE translation of the manga sequel to the Ring.

http://www.nensha.net/rasen.html

I'll have to check that link out. I read Tomie 1 and liked it, but I thought Uzumaki's art and story was better. It could have been the print quality too I think the print quality on Tomie wasn't so hot.