Check out Darren Shan. Guys a great young adult writer. he even has some mature books for the 20 something year old readers (albeit they are a little slower paced)
check him out I own about 7 of his books
http://www.amazon.com/Darren-Shan/e/B001IGODB2/ref=sr_tc_2_0?qid=1373121295&sr=1-2-ent
