In alignment with their corporate mission statement “to organize the world’s information and make it universally accessible and useful”, Google Books boasts the world’s most comprehensive index of full-text books. It also allows users with Google Accounts to create a personal library as is shown in the image for this post (blue text, beneath the search bar). Google Books also allows for the borrowing of certain books.
Language tool is a nifty website for checking the grammar of text passages under 20,000 words. In the free version, the website states that it has thousands of patterns it uses for finding errors. It also exists as an add-on for Google Docs.
Librivox boasts an impressive library of 5,000 audibooks read by volunteers from all around the world. All books are completely free and can be listened to on a large range of devices. The search feature supports searching by author, title or reader.