Have recently become a fan of One Piece... Also am collecting various manga. Not a huge collection (only a hundred or two books), but I _am_ working on it.
I own the entirety of: Petshop of Horrors, Tokyo Babylon, Fake, Dragon Ball
Am working on collecting: Bleach (21 volumes), Yami no Matsuei (4 volumes, also called Descendants of Darkness), Ranma 1/2 (3 volumes), Fullmetal Panic (4 volumes), Fullmetal Alchemist (16 volumes), X/1999 (16 volumes), Mega Tokyo (4 volumes), Sorcerous Stabber Orphen (4 volumes)
I get the feeling that I'm forgetting something... *sigh*