www.example.com vs example.com
Is there any particular reason that "www." is required for some websites? It seems to me that all this does is cause inconvenience (at best) and confusion.
For example, http://math.cmu.edu gives a "Server not found" error, but http://www.math.cmu.edu takes you to the right place. Also, on HD Nation (Revision 3) they advertise for Netflix, but warn that you need to include "www." for the show-specific URL and discount to count.