Below are several sites that allow you to read books on your tablet, phone, or computer.
Baen Free Library - Small library of short stories - mostly the first of ongoing series to get you hungry for more.
Project Gutenberg - The first to convert public domain works into a digital format, offering over 50,000 free ebooks: choose among free epub books, free kindle books, download them or read them online.
Manybooks - A large selection of books and genres to select from.
Read Easily - Ebooks specifically with the elderly and somewhat visually impaired in mind. You can change the color, fonts and size of text to make it easier to read. Books cannot be downloaded