Public domain books have been around for a long time, but until efforts like Project Gutenberg came along, getting your hands on them was no different than any other book: you'd have to check it out from the library or buy it at a bookstore. After Gutenberg and Google Books, they were free and plentiful, as long as you didn't mind reading giant 19th century novels on a computer screen. But if you were one of those people who prefer their classics in audiobook form -- and if I had a massive commute every day, I might be -- there was no free option.
Then, a few years ago, a Canadian fellow named Hugh McGuire dreamed up an idea for a website that was a bit like Wikipedia, but for audiobooks. Volunteers would record themselves reading public domain classics, upload them, and other volunteers would proof-listen them for errors and such. What started off as a few dozen recordings in 2005 has grown to a library of more than 4,000, with between 60 and 100 added each month; LibriVox claims that such stats make them the most prolific producer of audiobooks on the planet, and they might be right.
They've got plenty of classics -- like Pride and Prejudice and Hardy's Return of the Native, their most downloaded recording -- as well as books in 33 languages besides English (here's The Analects by Confucius, read in Chinese) non-fiction (Karl Marx's Capital poetry (Rime of the Ancient Mariner) even logic and philosophy -- here's Prior Analytics by Aristotle. In other words, enough to keep you listening for the rest of your days.
There was a time, back in the ancient days, when all human knowledge was knowable by a single person. Sites like this -- and the Internet in general -- drive home just how long-gone those days are.