OverclockWidget (Need Root)

It can help you make the CPU run as your wish and monitor the current CPU speed. It can be a speed monster, or a battery saver. It runs similar to setcpu, and when full speed, can speed up your game performance, such as Angry Bird, Cut the rope, Fruit Ninja etc... when set to lower freq, it can enlarge your battery life.

This free app is ad supported and may contain ads in the notification tray.
BUT YOU CAN CLOSE THOSE ADS IN ADVANCED SETTINGS AT ANY TIME.  SO IF YOU HATE AD, BUT DO NOT CLOSE IT, DON'T BLAME ME.

Three modes: Screen On/Screen Off/Charge Mode

Support both phone and tablet, dual core devices support.

AWARE: NEED A ROOTED PHONE OR PAD! Support up to Honeycomb!
AWARE: User can switch off/block all ADs any time!
AWARE: Sorry, all current MTK base devices were not supported!