There are many digital libraries on the web where one can access books in the public domain, freely. The grand daddy of all is the Project Gutenberg at http://www.gutenberg.net. It is the original free digital library of books no longer in copyright. Here you can find a great many classic literary texts here.
The full Gutenberg collection now exceeds 5,000 books. The Project Gutenberg philosophy is to make information, books and other materials available to the general public in forms a vast majority of computers, programmes and people can easily read, use, quote, and search.
Inspired by Project Gutenberg there are now a plethora of digital libraries on the web. Among them are The 'Alex Catalogue of Electronic Texts' at http://www.infomotions.com/alex , a collection of public domain documents from American and English literature as well as Western philosophy.
Here, one can search the content, and also create on-the-fly PDFs for offline reading or printing. Cornell University's 'arXiv e-Prints' at http://www.arxiv.org provides e-Print "preprints" in physics, mathematics, nonlinear sciences, and computer sciences.
The arXiv's mirror sites are in many countries, including India. CogPrints, the Cognitive Sciences Eprint* Archive, at http://cogprints.soton.ac.uk, provides access to a wide variety of papers in psychology, neuroscience, linguistics, philosophy, biology, medicine, anthropology and computer science. Some areas of this e-archive requires registration to obtain a username and password.
'The Complete Works of William Shakespeare' (minus his poetry at present) can be read either as a continuous text or by individual scenes at http://the-tech.mit.edu/Shakespeare/works.html. The 'Ebooks Online Library,' at http://www.readeasily.com/ has books of a dozen authors ranging from Aesop to Sun Tzu. The books are hosted here in HTML format for online reading, all of them sourced from Project Gutenberg.
The visually impaired and older readers would find the texts easy to read as the font size, colour, or background colour can be set, easily. 'The E Server,' at http://eserver.org, an arts and humanities e-publishing co-op, is based at Iowa State University where hundreds of writers, editors and scholars gather to publish over 35,000 works free of charge. '
The Great Books Index' at http://books.mirror.org/gb.home.html has links to online works, in English translation, by more than 130 classic authors, from Aeschylus to Virginia Woolf. This is truly a great endeavour of Ken Roberts of Ontario in Canada. At the 'Internet Public Library' over 20,000 free books can be accessed at http://www.ipl.org/reading/books. The IPL Online Texts Collection contains over 20,000 titles that can be browsed by author, by title, or by Dewey Decimal Classification. Kurt Stüber's 'Online Library' hosts a large library of books on biological subjects, many currently out of print and hard to obtain. Mostly German authors, but luminaries such as Charles Darwin are also included.
You can browse the collection by author, title, category or publication date at http://www.zum.de/stueber/. 'The Oxford Text Archive' at http://ota.ahds.ac.uk/ works closely with members of the Arts and Humanities academic community to collect, catalogue, and preserve high-quality electronic texts for research and teaching. The OTA currently distributes more than 2000 resources in over 20 different languages, and is actively working to extend its catalogue of holdings. The 'World eBook Library' at http://netlibrary.net/WorldHome.html permits free, unlimited public access to a comprehensive collection of public domain texts and references, and links to thousand of on-line libraries around the world via the World Wide Web and/or Telnet.
For a small annual fee, it also offers access to over 60,000 PDF e-books and e-documents, plus 7,000 mp3 audio books. There are several Indian endeavours as well to provide free access to books on the web. These include 'Free Indian e-books,' the Digital Library of India which was inaugurated by the ex-president of India, Dr APJ Abdul Kalam in late 2003, now has more than 29,000 books at http://www.dli.ernet.in/. It aims to provide a free-to-read, searchable online collection of one million books, most of them in Indian languages. The 'Universal Library' (under development) at http://www.ul.cs.cmu.edu is a far-reaching initiative of Carnegie Mellon University and the governments of China and India. This million books project, to supplement the formal education system, will have considerable content in many Indian and Chinese languages, as well as English. At http://www.cs.colostate.edu/~malaiya/hindipoets.html you can read the works of Hindi authors and poets, from Amir Khosrow to Faiz Ahmad Faiz, Sahir Ludhiyanavi to Javed Akhtar. To read some of the poetry you may have to install Hindi fonts in your computer. 'Project Madurai,' a work-under-progress Tamil Digital Library, can be found at http://www.tamil.net/projectmadurai/. This is a voluntary effort, has over 240 works in Tamil script, mainly old Tamil classic works. These have been made available, in TSCII (Tamil Script Code for Information Interchange) format.