In my case, smellsofbikes, showing off that I run my own domain is the key point. I'm a web professional, and my email address' domain name is the same as my blog, so it serves a dual purpose. First, it immediately identifies the fact that I have the know-how to run my own site (obviously useful in my line of work). Second, it provides free advertising for my blog to anyone with whom I correspond. Either is a great way of boosting my profile in the eyes of potential employers and clients.
Your point about woz.org is an interesting one. I would argue that impressing average users is irrelevant, at least as far as personal branding goes. What really matters is impressing the handful of people with whom you need to build trust and authority. If your email address can help you pull that off, I'd say it's a big plus.