Here, are some useful websites, practical references and valuable works that are now in the public domain.
Sivananda Daily Readings - The readings are the best way to begin the day! Each day, you will receive a page-sized teaching from the writings of Gurudev Swami Sivananda. This wonderful work was compiled by Swami Venkatesananda from 77 books of Swami Sivananda and masterfully arranged to be content progressive. Messages are sent the morning before for the next day’s contemplation so as to accommodate members located in various time zones. Special messages are sent on Saturdays from the writings of Swami Sivananda.
My YouTube Channel - You can subscribe if you are interested in being notified when there are any updates.
Internet Archive - You can find many wonderful books that are in the public domain on this website. You can download them in pdf or other formats.
Librivox - Here, people record books that are in the public domain and make them available for free to all. For instance, try searching 'James Allen' in the author search, you will see some of his audio books there.
Vairagya Shatakm of Bharatrihari in Poem - This is an excellent poetic rendering of Bharatrihari's 'Vairagya Shatakam'. Often, the rules of prose do not allow subtle points to be highlighted as well as poetry which is not bound by prose's rules. Sivananda-Usha has brought out this little text's subtle points beautifully. Download: pdf for print / eBook for readers)
From the Introduction...
Startling it is somehow to grasp how the life struggles of ancient times as portrayed in the Upanishads, the Bhagavad Gita, in all of the scriptures, and in the writings of the sage Bharatrihari, pertain—in precise detail—to this very moment of our struggles and concerns.
In the hundred poems of Bharatrihari, paying homage to Shiva, the Light of Knowledge, at the very outset, are reiterated the maze of entrapments of earthly life and their consequences—all the while he beckons us towards discrimination, meditation, and ultimately transcendence—that we may take up the glorious way of the wise, like the sage who knows the 'bliss of self-possession' and ultimately merges in the Supreme Brahman.
Swami Sivananda reveals to us, in glorious word and song, the great and comforting promise amidst every teaching imparted: that the Self may be realised by one who lives here in the world!... that the Self may be realised in this very life!
From the Public Domain
Books found here are in the public domain and not under copyright. I am placing them here as I feel these will be more convenient to share in one place.
The Thirteen Principle Upanishads translated by Robert Ernest Hume (pdf scan of the original book, 30.5mb) - this is an excellent and accurate translation of the principle upanishads without interpretation or commentary.
Treasure House of the Living Religions by Robert Ernest Hume (pdf scan of the original book, 2.5mb) - though an older book, it is an excellent compilation of teachings from different religions under three major headings.
The System of the Vedanta by Paul Deussen (pdf scan of the original book, 10.5mb) - here is an excellent work based on Sankara's commentary on the Brahma Sutras.
The Bhagavad Gita translated by Edwin Arnold (pdf format, .5mb) - a very inspiring poetical rendering of this timeless scripture.
The Light of Asia by Edwin Arnold (pdf format, .5mb) - excellent poetical rendering of the Life of Buddha.
Poems of Inspiration, Courace, Cheer and Faith collected by Joseph Morris & St. Clair Adams (pdf format of the original book, 29.5mb) - one of my favorite collection of poems in one book.
Copyright notes: The books are in the public domain and have been downloaded from the Internet Archive. If you feel you have the copyright to these works, kindly contact me and I will remove the books you hold copyright to.