X-link to the DRM-free thread for the new Humble Bundle with some non-fiction content:
Humble Comics Bundle Jack Kirby & Will Eisner Centennial Celebration contains a number of prose history books and magazines exploring the works and legacies of the pioneering comics creators and early North American superhero comics in general. TwoMorrows Publishing's industry spotlight issues are generally very good indeed, and there's also a nice looking book on the Stan Lee/Jack Kirby collaborations which founded Marvel Comics, among other things.
Also, the
Humble Book Bundle Stranger Creatures Supporting the Jane Goodall Institute which has some non-fiction animal wildlife titles at the top tier, including the noted primatologist's classic memoir, is still available.