Price: Free ($1.99 to unlock Pro)
Platform: iOS Universal
When I heard about extensions the first use I thought of was a clipboard manager. I wanted to copy multiple bits of text from an article and then add them all to a text document at once. Clips does just that with an extension, keyboard and Notification Center widget. I copy some text, bring down notification center, tap the plus and it's added to my Clips app. The best part of the app is the clipboard keyboard. It allows me to save a bunch of snippets, flip over to Editorial or Evernote and paste a bunch of snippets all at once. It's a great experience that really improves a task I do quite often.