Auto-CPUFreq - An automatic CPU speed & power optimizer for Linux.
CPU Frequency Selector - Cinnamon CPU Frequency Selector Applet
Zzz - Zzz is a custom power management utility for Windows that is designed to eclipse built-in power management systems.
Prime95 - Prime95 is a program that searches for new Mersenne prime numbers.
PowerTOP - PowerTOP is a Linux tool to diagnose issues with power consumption and power management.
HeavyLoad - The individual test methods employed by HeavyLoad can be customized to fit your needs.