Doujin (mature audiences)

Some good shizzle:http://www.browsehentai.com/
http://doujinland.com/
http://www.tadanohito.net/news.php

most doujin arent r-18 or a bit like hentai
its those pervy soon to be manga artists who wants to see their fave manga babes doing naughty stuff

sumtime i just lurk mine at *coughcoughcough4chancoughcough* lol
mostly i google for yuri doujin >/////> ''
but if yer and advance fan of certain animu .. u guys will mostly know where to get the good stuffand .. doujin is not H stuff lol
it depend on what genre u .. read : /im in for sum 4koma/panel too :33

Third on that, Doujin does not mean hentai. Doujin I thought refers to amateur artists drawing out fanfiction and it can be anything. Although for a lot of fujoshi targetted doujin are Boys Love manga based on characters from all kinds of manga.

go to www.fakku.net..
have LOTs of hentai collection here!!!
Anime and Manga..as well Games...need to Register..a five star website!!!or go to www.hentaigeeks.com..
it's a forum and lots of people upload it and with large selecion..
just sign up and you're ready for it..or go to www.browsehentai.com..
a MORE larger collection!!
just beware what you click though...hehe..or Lastly(there's more..but I give four only..)
go to www.thelurker.net..
this is IRC based download..
where you using a mIRC or other chatting software to download hentai manga..convenient..huh..
just write down the number and *press button*..it will download..
but it's slow..depending on your connection....

http://doujin-moe.us
has a very large collections of naruto, bleach, one piece.. gundam.. zero no tsukuimi, clannad.. etc..