Dragonhead by Mochizuki Minetaro.
A dark, gripping and simply fascinating psychological horror/apocalyptic masterpiece:
http://www.manga-sketchbook.org/projects.php?id=4
Only available in IRC at the moment and sadly on hold at Volume 4.
I'd also recommend Kiseiju or "Parasyte" by Hitoshi Iwaaki (released by Tokyo Pop in the US), it might be a little graphic in some places but its an excellent observation of the human condition and what it is that makes us what we are:
http://www.tokyopop.com/dbpage.php?p...tegorycode=BMG