WordBoard Keyboard is a free iOS application which allows you to personalize and pre-program your keyboard. You can add a key to automatically type your email address, postal address, hashtag, an email template reply, ASCII art or anything else you can imagine.
The PRO version allows you to import your recent hashtags on Twitter and Instagram and import emails, phone numbers and addresses from your contacts.
Requires iOS 8.1 or later. Compatible with iPhone, iPad, and iPod touch. This app is optimized for iPhone 5, iPhone 6, and iPhone 6 Plus.