Android/iOS: Paper books are awesome, but sometimes there's no beating the portability of an ebook on your phone or tablet. If you have a physical book you'd love to read on the go, BitLit may be able to get you an ebook version for free—all you need to do is take a photo.
Here's how it works: Install the app on your iOS or Android device, then use the camera to take a photo of your bookshelf (the service calls this photo a "shelfie," a groan-worthy phrase we'll only repeat once.) Then, BitLit identifies the books on your bookshelf and lets you know which ones are eligible for free electronic versions. To claim an ebook copy of your physical book, you'll need to take another photo of the physical book, with your name written in it, in pen. This extra step is designed to stop people from just taking pictures of libraries or bookstores and claiming tons of books they don't own—and it's also designed to let you claim a book once but read it forever. Once your book is claimed, you can get the ebook copy sent to your Kindle, Kobo, Nook, or just read the PDF if it's available.
The app and service itself is free, but it's important to note that not all of BitLit's ebooks are free. Some of them you'll have to re-buy, which is mostly how the service makes money. Unlike previously mentioned Amazon Matchbook however, it doesn't matter where you got the physical books from—you can still see if the electronic versions are available. Hit the link below to read more, or try it out.