One of the things I like to do before leaving on another trip is to load up my iPod with a variety of entertaining and informative podcasts. If you use iTunes, and have not yet discovered this, give iTunes U a look. There are hundreds, if not thousands, of fascinating lectures and podcasts for some really great campuses, professors, and schools.
In fact, there are more than 30,000 audo and video files to keep your attention, whatever field of academic interest you feel like pursuing. Keeps the old grey cells working!