As a student books become a way of life as a result I have strained tendons in my left wrist from hauling weighty tomes around. So the idea of being able to access my books on line is a very attractive one. I have been researching possible sources. Here is a list of initial contenders which I have yet to research fully.
This a site I have used and works well. Also known as Google Book Search, there is a wide range of free book and magazine content, much of it downloadable. Occasionally they allow partial download of copyright restricted books. I found it good for contextual studies literature.
Out-of-copyright classics, most are free.
A source of downloadable textbooks, saved as PDFs, meaning that unlike most electronic book formats, the diagrams and illustrations are preserved. Most take less than 60 seconds to download over broadband.
Find items in libraries near you, lets you search the collections of libraries in your community and thousands more around the world. Results link directly into citation software such as Zotero.
World Digital Library
Libraries and archives from around the world have come together in a project to share their collections of rare books, maps, films, manuscripts and recordings on-line for free.
The first and largest single collection of free electronic books. From Karma Sutra to David Copperfield.