Zettai Karen The Unlimited
A powerful user of psychic powers begins gathering others like him in an attempt to change the world. The series is fine for action; watching people, tanks, and entire cities get destroyed by telekinesis never gets old. But what really sells the series is a strong main character that has both determination and a certain charisma to keep the audience rooting for him the whole way through.
Speed Grapher
A war photographer finds himself with the ability to make objects (and people) explode by taking their picture. If that summary doesn't sell you on this series then I don't know what will. It's quite a weird ride, full of eccentric assassins and crazy superpowers. But underneath the zany exterior, there are some more hard-boiled themes to be had which rounds out the experience nicely.
Claymore
Humanity lives in fear of the Yoma, shape-shifting demons that can blend into society before murdering and consuming the organs of human bodies. To counter these beasts are swords-for-hire known as Claymore who can sense Yoma and cut them down. If you like swords and blood, you've come to the right place. (And I strongly suggest reading the manga if you enjoyed the anime.)
Deadman Wonderland
I'll preface this recommendation by saying the manga is scoring better than the anime adaption, though this series has its pluses. Anyway, Ganta is framed for the murder of his entire class and is sent to a massive privately owned prison where the only way to survive is participating in games of life and death. It's a short series, but still a lot of fun if you enjoy violence and superpowers.