The ability of the Android OS to perform “true multitasking” has always been one of it’s major advantages over the other two major mobile platforms. Even though the others have finally caught on, Android’s approach still offers many advantages over both WP7 and iOS in this respect. Of course the OEM’s have each put their own spin on this functionality and alter the default AOSP multitasking experience, but the fact remains that you can keep applications running in the background as you see fit and switch between them fairly easily.
XDA Forum Member kbzium has developed an app entitled Taskbar Switcher which allow you to replace or supplement whichever incarnation of the multitasking system you are currently using. The way it works is simple: recent and still running applications will appear in your notification tray, and a subtle yet obvious dot for each will also appear on the taskbar. If your not keen to have your entire tray swallowed up by running apps, the number of remembered task can be set to suit your needs. Apps can also be excluded from being remembered.
While this may not be something you wish to have running at all times, Taskbar Switcher has the option to control whether or not the application is launched at startup. Definitely worth a look if you are unsatisfied with the way multitasking is currently implemented on your device. Taskbar Switcher requires Android 2.1 or above and can be found in the original release thread._________