You're describing a world where everybody expected a website to end in .com, and if not that, then maybe a handful of others. That world is changing; what will people's expectations be in the future?

My blog has the URL http://boston.conman.org/ (leaving http://www.conman.org/ for other stuff on my website). I had to add a redirect for http://www.boston.conman.org/ because I had a non-zero number of requests.

This is a good point. Any subdomain that you host web pages on should itself have a www sub that redirects, for this reason.

I've seen some sites that redirect to m.example.com if you're accessing them from a phone. Do you think people are getting confused by that?