Auto pops up the USB tethering settings menu when the device is connected to a USB port (but not when connected to an AC charger), so tethering only requires one click. As far as I know, there is no way to enable USB tethering automatically after plugging in the device. This is the next best thing. When you connect your Android device to your computer, the tethering menu will open automatically. This will only work on devices that support UMS (USB Mass Storage). If your devices does not support UMS (for instance, if it uses MTP instead), use the Non-UMS compatibility version of this app.
I will give all of my paid/ad-free apps (both my current apps and any future apps) to anyone who provides me with a translation of one of my apps or the Play Store description of one of my apps. I'm interested in any language. Send your translation to the email address provided by the "Email Developer" link.
Note: The app seems to be crashing on a very small number of devices. This is not because there is anything wrong with the app, so please don't write an angry review. The crash is caused by these devices not having the class com.android.settings.TetherSettings. This is either because these devices are running a version of Android older than 2.2 (which will not work), or because the devices are running a manufacturer/carrier modified version of Android that is missing that class (maybe because the carrier didn't want people tethering their mobile Internet connection). If you're experiencing this problem, send me an email with details about your device, and I'll try to find out if I can fix this.
1.0.1: Using the setting to disable the app's functionality will work now.