Office Lens, which was released in a semi-private beta in April, is now widely available through the Play Store. The app had been on Windows Phone for quite a while and, continuing their pattern, Microsoft decided they wanted it on Android as well. Office Lens uses your phone or tablet's built-in camera to scan documents or whiteboards and convert them to PDF or office document formats. Here's an example of how it's supposed to work from the app info:

Of course, lots of things will affect how well it works in your experience. The lighting, the quality of the camera, steadiness of your hands, and untold other factors may result in far less success than Microsoft's example images.