GTO- Great Teacher Onizuka - An ex-gangster goes back to school to become a teacher. The thing is the students are chaotic and even dangerous. But the martial arts master / pervert / heart warming Onizuka sets everything right with his fist and what little smarts he has <~~>
(Just read GTO!)
Vagabond - Follows the story of Musashi and how he became one of the greatest samurais of Japan during his era. The art is amazing, the fighting scenes are really well drawn with power and gore.
Ares - A Korean Manhwa. Story revolves around 3 people that meet in a war. They each have a hidden past, and reasons for what they do. This is a good series with non stop fun, and it has good funny moments at random times.
Eden - Its and Endless World - I can never really describe this series too well. Its set in a near future, where a virus has began a slow and eventual death of the human race. The story follows a boy whos father is a crime lord, but it isn't an easy world for anyone. What I can say is that this has one of the most original and interesting plot out there.
Monster - Psychological, Mystery, Death, Human Nature, Pain, Greed, Right, Murder, Life, Doctors.... well thats all I can say about monster. My descrip doesn't do it justice, but its something you'll have to check out. Its finished though.