The anime started airing in Japan this past October 3rd 2006. The story of D.Gray-Man takes place in a fantasy 19th Century. Where the Millennium Earl is trying to cleanse the world by using Akuma, made to destroy all humankind.
This is where Allen Walker, an exorcist comes in, and also a new member of a group of exorcists called the Dark Religious Organization. Their job is to put a stop the Earl's plans.
The exorcists themselves are gifted with Innocence, a divine substance created in the ages past to combat the Earl's minions, the Akuma. There is said to be 109 units of Innocence in the world and once an Innocence has found its compatible person, it will evolve to become a weapon to fight the Akuma.
D.Gray-Man at the time is still coming out in the Japanese Weekly Shonen Jump and is being translated by Timcanpi, the manga is now licensed by Viz. If you have not read D.Gray-Man before I think it is really something you should look into. The storyline is very good and the characters are very cool. Hoshino Katsura's drawing is also something worth looking at as well. So if you get the time and are looking for something to read, read D.Gray-Man you won't be disappointed.