The Hunger Games trilogy by Suzanne Collins (I'm counting it as one). I would recommend this book series because they are intense, gripping and addictive. They also have excellent literary clout as they show when government becomes too powerful, what it means to be human, and the cost of war. Very good series.
The Chaos Walking series is another good book series. It deals with the idea of every guy's thoughts being broadcast all the time, or, as the author put it, information overload. From there, it takes a boy who is about to become a man running from the dark secret of his town. Another good book that looks at what it means to be a terrorist and what it means to have power.
The Mortal Instruments series I would recommend to some people, though I'm a little hesitant. It bears a lot of similarity to Harry Potter, but I think what makes it worthwhile is it can be quite funny and it doesn't drag. Basically, Clary is pulled into the supernatural world of the shadowhunters and she discovers that she's a pivotal player in a sinister plot to overthrow the order. It's got one of the most sizzling, taboo romances as well. The fifth book in the series comes out in May.
The Pact by Jodi Piccoult was one of the most powerful books I'd read in a while (with the exception of the Hunger Games). It deals with a suicide pact and teen depression. Piccoult describes the premise of the book as a reverse of Romeo and Juliet by saying it's about two families that became too close. Basically, Chris Hart and Emily Gold have known each other ever since they were babies and everything seems to be going fine until the day Emily turns up dead from a suicide pact she made with Chris. The book is intense and I stayed up all night reading it to find out what would happen. The characters are well developed and you're constantly trying to figure out what happened.
Unwind by Neil Shusterman was a very though provoking book. It deals with the consequences of a war between Pro Life armies and Pro Choice armies in which, starting at 12 and ending at 18, a person could be "unwound" or have all their body parts donated to other people. I would recommend it because of the interesting premise and look at society, what happens when life becomes too cheap and the action is suspenseful so the book doesn't drag too much.