When email and SMS notifications just do not cut it, send yourself push notifications of form submissions with Pushover. Pushover makes it easy to send real-time notifications to your Android and iOS devices.
With customizable titles, messages, sounds, and priorities you can completely customize the way you are notified by your form submissions. Send leads to yourself by normal priority, and send SYSTEM DOWN!!! type notifications to yourself with emergency priority where you keep receiving the message at an interval you specify until the message is acknowledged.
This extension requires the Pushover app for your mobile device.