Android Overclock is described as 'Droid Overclock allows full customization of CPU frequencies and adds a ton of extras to your rooted experience. You can overclock to increase speeds or underclock to save battery life. Set custom profiles to increase performance to the max' and is an app in the System & Hardware category. There are three alternatives to Android Overclock for Android and Android Tablet. The best alternative is SetCPU. It's not free, so if you're looking for a free alternative, you could try CPU Tuner or Nook Color Tweaks.
CPU tuner gives you control over the power consumption of your Android device. Its prime purpose is to save as much battery as possible, but it can be used to overclock at the same time (if the kernel of your device supports it).