Android: Seeing how fast your CPU is cranking is just a keyboard shortcut away on Windows. It's not as convenient on Android -- unless you use Usemon.
The app puts an at-a-glance system monitor directly in the notification shade of your device. Just swipe down and get graphs for CPU, RAM, network and disk usage. You can adjust which stats are shown in the shade (or disable them entirely) from the settings. Or you can deck out your shade with our previous roundup of notification shade apps.