Manga Database is a large collection of Manga, Hentai and Anime sets from the US, UK and Japan. The Japanese stuff is actually written mostly only in Japanese without any translations, so it might be difficult for some fans to enjoy it, although I know the pictures speak volumes anyway. The quality of the artwork tends to be high. They describe content as being exclusive, but some of it might be unique only to the network, not to the individual site, while some images appear to be scanned from print materials.