Blood+

I've been watching fansubs of this series for months and I can honestly tell you its a very good show.
Its based in the same universe as the movie Blood: The Last Vampire.
I haven't seen the movie but I know that this series has better graphics and obviously a much longer time frame to tell its story.
The story centers around a girl named Saya and her family and friends while they battle the Chiropterans aka vampires that are threatening the world.
The story takes us around the world and introduces us to many very interesting characters even Saya's long lost sister who shares some of Saya's "special" characteristics but not her compassion for life.

Here are a few sites that will give you a little info about Blood+:
http://en.wikipedia.org/wiki/Blood%2B
http://www.imdb.com/title/tt0482855/
http://www.productionig.com/contents/works_sp/20_/

Here's a few reviews of the series as well:
http://www.animenfo.com/review.php?id=1715&n=nabfka&t=blood_&type=anime

This series is being released on DVD in the US soon if it sounds interesting to you.