The first manga scanlation site that I have found is called Direct manga. This site has gained a lot of popularity lately so the d/l has not been easy on their servers or to the users. Here's another manga scanlation site called Manga download that you could use as alternative to download some popular manga's.
Manga download has 666 Satan, AirGear, Black Cat, Blood The last vampire, Death Note, Elfen Lied, Fire Candy, Fullmetal Alchemist, Girls Bravo, Houshin Engi, Hunter X Hunter, My Name Is Zushio, Parallel, Pretty Face, Ragnarok, Yakitate Japan, Zetman. The comic library is not as huge as Manga direct but they do have some quality title. Go visit the site if you are into mangas.