Adhesive notes for iPhone. We know what you're thinking -- there are apps for that. Well, it's still easier to jot something down on a sticky note, and more satisfying to cross off an item with real ink. With Paperback, you can do a quick sketch or make a list the old-fashioned way, and slap it on the back of your phone. Use them one at a time, or put a small stack on the back of your phone to use later. Paperback's pages have a removable adhesive on most of their surface, keeping the note flat on your iPhone.