A very interesting episode of CBC Radio's excellent Quirks and Quarks show dealing with human happiness. Current research seems to show some interesting things about how we get happy and why we can never be fully happy but we're always striving for it. Check it out here: The Science of Happiness.
And speaking of excellent radio, if you haven't checked out This American Life, run, don't walk to a browser near you and listen to it. The Our Favorites page is a good place to start for some high quality work, although almost every episode is a gem... You'll thank me. Or not. Whatever...