This Android Quick Tip™ is actually two tips in one! Unlike some "other" smartphones that just barely added the ability to multi-task to their OS, Android has had it since day one. On Android you can run many, many apps at the same time, and using this often-overlooked tip, you can easily and quickly switch between them.
To do this, tap and hold the Home button: a grid of up to 6 of your last run apps will open, tap an icon to switch to that app. But what if you're a power-user and want to be able to quickly switch between more than six apps? You can always go back home (to your launcher) and launch the app from there, but if that's too time consuming, grab CyanogenMod 6 which ups the default number of recently used apps to eight ... but also gives you the option to increase this to 12, and even 15. Check out the video to see how!