When the device is USB plugged Easy USB Tethering automatically opens up the Settings' page "Tethering and portable hotspot" so you can activate the tethering service with just one tap. You can get rid of the pop-up using the back button.

Features:
- activated when USB plugged to a device that needs data connection and not in the case of a mere battery charger;
- very small amount of memory required in the target device (about 50KB);
- open-source (GPLv3) so you can build your own APK with the source code at https://github.com/double-m/easy-usb-tethering (using both Gradle and Maven);
- no advertisements.

Successfully verified on:
- Wiko Iggy (Android 4.2.2 Kernel 3.4.5)
- Samsung Galaxy S5 (Android 4.4.2)
- Samsung Galaxy Tab 2 (GT-P3100 Android 4.2.2 Kernel 3.0.31)
- Samsung Galaxy S3 mini (GT-18190N Android 4.1.2 Kernel 3.0.31)