Discussion on:

Five apps to help you clean up your Android device

Not a Free app, but the monitoring capabilities on the paid version are worth the price. The monitoring doesn't eat much as far as resources, but gives you a look at system/app performance over time. Nice for tracking the rouge app that freaks out on occasion and drains every resource in site

The free and $3.49 versions of Watchdog Task Manager will show you which apps are hogging your CPU, alert you when an app is using a lot of CPU, notify you which apps can most likely be moved to your sd card - and move them for you.

Thinking more about smart 'phones for this one.
Again, a free and paid version are available.
It lets you kill off all those apps. that have started in the background.

I think, 1-Touch Cleaner is also very good app for cleaning apps cache, call logs, messages, browser history and clipboard.
You can download it from Play Store (https://play.google.com/store/apps/details?id=com.probcomp.touchcleaner)