I hate typing in my password every time I want to install an application on my iPhone. My fat fingers make it so that I rarely get it correct the first time. If you're like my mom, you might not even remember it. Keyboard shortcuts are not a viable option either, since they are disabled for passwords.
If you're ready to not worry about your iOS App Store password ever again, then PasswordPilot by Filippo Bigarella is what you'll need. You'll enter your password for the last time in the preferences, then be done with it for good.
After installing PasswordPilot, locate the preferences in your stock Settings app and just enter in your Apple ID password for the last time.
Now, when you attempt to install an app from iTunes, the password will automatically be filled in for you.
And don't worry, the app uses what the dev calls "NSA-approved encryption standards", basically saying that the information is not stored in plain text so it's not easily readable.
The tweak itself is simple, but it's one of those little things that you appreciate after using it.
PasswordPilot Pro is available for $2 for devices running iOS 6 and below. The Pro version allows for multiple account passwords.