As you already know Android is a open sourse OS. This means that anybody could make an app for Android. This means that you could download an app that contains spywear or any bad program. So i have found a few links that will help you keep safe while using your phone or tablet.
http://www.gottabemobile.com/2011/08/24/5-anti-malware-and-antivirus-apps-to-keep-android-safe
/http://http://www.gottabemobile.com/2011/08/19/state-of-mobile-malware-shows-rise-in-attacks-infographic/
http://http://androidforums.com/android-applications/36936-how-safe-find-trusted-apps-avoid-viruses-guide-those-new-android.html
http://www.gottabemobile.com/2011/08/24/5-anti-malware-and-antivirus-apps-to-keep-android-safe
/http://http://www.gottabemobile.com/2011/08/19/state-of-mobile-malware-shows-rise-in-attacks-infographic/
http://http://androidforums.com/android-applications/36936-how-safe-find-trusted-apps-avoid-viruses-guide-those-new-android.html