I chose virtuallybing as my online identity to be consistent across the dozens of web services I use. While I'm not a fan of the term personal brand, it's essentially what I've created over the course of the last couple of years, and it's served me well. You should do the same if your online presence is important to you.
As many things are, virtuallybing was born out of necessity. While you may think my given name is unique, it isn't. When I signed up for Twitter I ran into another Bing Chou, a tennis instructor in Toronto, who had already taken the handle @bingchou. I soon found out that the domain bingchou.com was taken as well and that there are several Bing Chous on Facebook and LinkedIn. My parents lied to me when they told me I'm one of a kind.
I chose virtuallybing after seeing it was available as a username across web services and grabbed virtuallybing.com right away. I've been able to sign up for new accounts for a couple of years now using Bing Chou when my real name is required and virtuallybing when it's not. Being able to use virtuallybing consistently across web services, especially social media services, has gone a long way in helping others remember who I am.
I'd recommend you find a username you can use consistently as well. If you're working hard to network or build your reputation in the startup community, it will go a long way to have a name that people will recognize as they come across your stuff online. Especially for the Michael Smiths and Bing Chous of the world.