Another couple of small non-fiction books that are rather similar to each other: Acquainted with the Night, by Christopher Dewdney, about night-time; and Latitude Zero, by Gianni Guadalupi, which follows the equator around the world and through history. Both good for small-dose history and anecdotes.

Another one a little heavier; The Island of the Color-Blind by Oliver Sacks. Offbeat and interesting.