The android tutorial adds its own application to system sharing

Configure a different type of intent-filter in your own AndroidManifest.xml for an activity. Here you are adding pictures, and you can also add other types

<intent-filter>
   <action android:name="android.intent.action.SEND" />
   <data android:mimeType="image/*"/>
   <category android:name="android.intent.category.DEFAULT" />
</intent-filter>