Fossils, Finches and Fuegians: Charles Darwin’s Adventures and Discoveries on the Beagle (Text Only) is a biographical account of Darwin during the voyage. The Kindle version lacks the pictures, but if you have Alan Moorehead’s Darwin and the Beagle then you probably have all those pictures. I’m not sure if this is a worthy addition to the average person’s library, but if you have all the Darwin books and don’t have this one, this is a chance to fix that for a mere two bucks.
Barbara Tuchman’s A Distant Mirror: The Calamitous 14th Century is available on Kindle for 1.99. It is audible enabled.