Ding! I have an OpenID (in fact, I have several, thanks to having accounts at a number of different sites that provide it, and keep meaning to set my own up so I've got control of my own ID) but I never use it, because it's as much faff as creating a username and password. If there was simply a button on my browser that I could click to say "identify me to this website", I'd use it a lot more.