The Science of the Hitchhiker's Guide to the Galaxy | 
pickI am enjoying multiple listenings to the audio version (not least due to it being read by Julian Rhind-Tutt). Although abridged from the original text it's is still four hours plus long. Written in a conversational style it easily weaves the ideas from Hitchhickers into the real world science, reflecting on the books influence as well as where science was when Adams was writing. Well worth a listen (or read).