Mostly Shonen stuff I've been reading. One Piece, Bleach and Fairy Tail being the main ones I follow. I occasionally also check up on Negima, but not as often as I used to, and Full Metal Alchemists monthly chapters gets quite irritating - I want more, now!
A very interesting series I read was called Parasyte, deeply disturbing artwork in certain sections, and a bizzare story that had me hooked for a while.
In the past I've also read Love Hina, and very little of Naruto, but thats about it as far as manga goes.
Interestingly, its only manga that I will follow over the long term, I tend to prefer shorter anime series, such as Haruhi, Death Note and Elfen Lied.