How to degrade gracefully when using add-on extension APIs to the core Android SDK framework. How to target multiple add-ons for a project. Techniques will be shown to provide compatibility not just across platform levels but across device capabilities. Also, a quick overview of the APIs for a specific addon, the HTC OpenSense SDK add-on will be presented with additional background on how an Android SDK add-on is created and packaged for those interested in creating their own add-ons. Also the new SDK tools capability of using templates for creating custom new project wizards will be presented.