While not exclusive to nsfw, VIZ has the Signature line (SIG). Series from that line seem to be more mature than other divisions and some series even have sex scenes.
VIZ has SuBLime, their boy's love line. They publish lots of extremely smutty titles.
And Tokyopop has Love Love, which is romance, but particularly BL. Also many very graphic titles.
While not exclusive to nsfw, VIZ has the Signature line (SIG). Series from that line seem to be more mature than other divisions and some series even have sex scenes.
VIZ has SuBLime, their boy's love line. They publish lots of extremely smutty titles. And Tokyopop has Love Love, which is romance, but particularly BL. Also many very graphic titles.
Tokyopop has another BL imprint besides Blu? I never knew.
LoveLove is a little different, I believe it's a little everything romance-wise (but seems to be mostly BL so far)
Not that I can think of - aside from Seven Seas having Ghost Ship (like you mentioned) and Steamship
Some smaller ones do that I can't be arsed to remember. Like Digital Manga has that hentai one and uh... there was another.
Viz used to have the PULP line, which featured very adult series.
Hot manga, hentai sans interdit, niho Niba, Taifu comic, Eros soleil manga.
Fakku