Tempest by Julie Cross

19-year-old Jackson Meyer can time travel.  Not much, usually just back a few hours or days.  And when he does go back, nothing he does actually impacts the future - no one remembers interacting with him if it happened on one of his jumps, if he hurts himself he isn't seriously damaged when he gets back, and if he does something on one of his jumps, like break a window, that thing is undone when he gets back to the present.  It's not really serving a purpose, but he's having fun experimenting, and keeping it a secret from everyone but his science genius friend who is helping him figure out why it's happening and how to use it.  At least it is all fun until some people who also appear to be able to "jump" back in time show up at his girlfriend's college dor, attempt to kidnap Jackson, and kill his girlfriend in the struggle.  Now Jackson has jumped back 2 years, farther than he's jumped before, and no matter how hard he tries, he can't get back to his "real" time.  And the Enemies of Time are still after him.

Divergent by Veronica Roth

In dystopian Chicago, society has been divided into 5 factions, each dedicated to cultivating a certain value:

• Amity (the peaceful)
• Candor (the honest)
• Abnegation (the selfless)
• Erudite (the intelligent)
• Dauntless (the brave) 

Crossed, by Allie Condie

Sequel to Matched.

Ready Player One, by Ernest Cline

Lots and lots and LOTS of geek and pop culture references from the 80's, as a teenage boy and his cohorts/competition attempt to solve puzzles in an online game that will determine who controls the internet in a futuristic society that lives mainly online.  Full summary from the publisher after the break.  Good for advanced teens and adults interested in the tagged subjects.  2011.

The Rise of Renegade X, by Chelsea M. Campbell

Damien Locke is all set for his 16th birthday - it's the day his life of crime officially begins.  It's basically a technicality - Damien's mom is the mad scientist Mistress of Mayhem, he is a shoe-in for Vilmore Academy, the ultimate school for teenage supervillains and he's already got his supervillain name picked out: Midnight Marauder.  But in Golden City, all supers have a letter appear on their hand on their 16th birthday to make it official - H for heroes and V for villains.  So imagine Damien's surprise when his V doesn't show up, but neither does an H; an X appears instead.

Only the Good Spy Young, by Ally Carter, Bk 4 in the Gallagher Girls series

In the previous three books in the series Cammie aka Chameleon Morgan has found out how serious being a Gallagher Girl is.  In the beginning it was fun knowing that she was a spy-in-training, sneaking out to meet a townie boy in Book 1 and using their special skills at detection, evasion, invention and deception to learn more about the mysterious boys from Blackthorne Academy in Book 2. 

Little Brother by Cory Doctorow