You took the words right out of my mouth! I have worked on dozens of sites in all different industries and the one thing that unites them all: Google Analytics traffic shows that many people punch in a full domain name into Google and rely on Google to display the result they want.

If your website is http://hackastack.com I doubt you'd go a month without seeing a referral from Google for a search for www.hackastack.com or something similar, even if you don't use 'www' on your site