Ok, so this is maybe not a light, summer read, but it is what I am reading this summer.
After a quick catch-me-up reading "The Girl with the Dragon Tattoo" and "The Girl Who Played
with Fire", I have moved on to the third in the trilogy "The Girl Who Kicked the Hornets Nest". If you enjoy fast-paced international thrillers filled with computer hacking sprites and espionage at the hightest government levels, these are the books for you. They're not in the used bookstores yet so you have to bite the bullet and buy them, borrow them from a friend, or head to your local library.
Any way you look at it, these books are a must read.