The last manga I've read was Lives by Taguchi Masayuki, same artist of Battle Royale. It's a very good concept, a real pity that it ended so abruptly! What's readable feels more like a prologue to an even better manga. It's only ten chapters long, so it's worth spending thirty minutes on.
My current favourite manga is by another legendary manga-ka, Mori Kaoru (maker of Emma), called Otoyomegatari. It blends romance and culture amidst AMAZINGLY DETAILED art. The first page alone contains detail porn on her outfit-- definitely a great series.
As for more popular mangas, I like to follow what's going on in The World God Only Knows as well as the Higurashi and Umeniko no Nako Koro ni series.