Gregg Hurwitz, Orphan X

Orphan X introduces Evan Smoak, a guy with gadgets and a particular skill set who's using his government-sponsored black ops training to help the helpless, one case at a time.

Evan was part of a secret program that turned promising orphans into lethal machines, but that period of Evan's life ended, rather dramatically. Now he's a modern-day Equalizer, waiting for calls on his secret phone while trying to avoid condo association meetings.

I loved pretty much everything about this book.

There are two more books out or soon to be out in the series, The Nowhere Man and Hellbent. There's also a short story, Buy a Bullet (but be warned that it is very short: most of what you get for your $1.99 at Amazon is a sample of The Nowhere Man. I wasn't happy about that.)