Right now I'm reading the A Song of Fire and Ice series.
I also second the Hunger Games series, seriously some of my favorite books, and they're coming out with a movie soon-ish.
Unwind by Neal Shusterman is probably my all time favorite book. Everybody should stop reading what they're reading right now and read this instead, because it is seriously amazing.
My all time favorite series/trilogy though is the Wind on Fire trilogy by William Nicholson. I never hear about the books from anybody else, and I feel as if I'm the only person who has ever read them, which is a shame, because they're truly awesome.