A jQuery plugin that adds delight to selecting multiple values for an input.
The recipients field in an email app is a perfect example. You could just offer a plain text input, requiring the user to manually separate each recipient with a comma. Removing a recipient, however, is a pain: the user has to precisely select just the right amount of text, making sure not to accidentally remove too much or too little. As a discerning developer, you know the user experience should be better. And it can be, with Manifest.