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. Features:

• Change cpu scaling settings (i.e. setcpu)
• Set cpu profiles with Screen off, battery percentage, temperature, screen on, charging usb, charging ac, changing/full.
• Gorgeous widgets with battery temp & cpu info
• increase speeds (overclock) or save battery life (underclock)
• Select scaling frequencies on the fly for supported phones
• Full overclock customization (set freq. and @ boot)
• Sexy and customizable UI
• Temperature notification options
• Voltage calculator
• Advanced settings (sysctl config, sampling rate, up threshold, other kernel tweaks)