Auto-fill every digital form
The extension: Lazarus
Have you ever filled out an insanely long online form, only to have missed one number on your credit card, resetting the entire freaking form? Of course you have, which is why there's that fist-sized hole in your drywall. Lazarus, cunningly named after that dude Jesus raised from the dead, dynamically saves what you're typing into any given form, and will replenish it intact, should disaster strike. Now that is truly saintly.