Built for tablets with support for dual-core processors, Tablet CPU Usage Monitor is great for monitoring cpu usage and frequency, when changing live wallpapers and other apps. This app has a very low resource footprint to help with battery consumption.
The interface is very simple and friendly, has statusbar notification for cpu usage, cpu frequency which can be setup in many colors, the app doesnt run while the screen is off and you can configure update interval. Runs in startup, and has full suport for Android Honeycomb. The app is available on the market for free and there is another paid version with more features.