The new free title for the Tor.com book club is Spin by Robert Charles Wilson:
The sun is now a featureless disk—a heat source, rather than an astronomical object. The moon is gone, but tides remain. A space probe reveals a bizarre truth: The barrier is artificial, generated by huge alien artifacts. Time is passing faster outside the barrier than inside—more than a hundred million years per year on Earth.
At this rate, the death throes of the sun are only about forty years in our future.
You can download the ebook from ebookclub.tor.com.
Edit: Amazon is giving away Wuthering Heights as the free ebook-audiobook bundle for November.
And Amazon Prime members can of course download one of six free titles.