I'm sure you've heard plenty about your personal brand. I think personal brands are important and that's why I use Gravatar.
Gravatar, a globally recognized avatar, allows you to keep your "picture personal brand" consistent on many platforms across the web. It's pretty simple - upload a picture to Gravatar's website and when you begin commenting on platforms it will automatically have your picture ready for the comments page; e.g. when you make a comment on a blog & use an email address you've registered, it will add your picture next to the comment.
I find this consistency helpful since your "picture personal brand" will become more recognizable & easily identifiable. I use the same picture here on my blog, on Twitter, Google, Gmail, other sign-ins like Wordpress sites, Gowalla and Foursquare, for example. When I update my picture, I make sure to update Gravatar first and then other sites to match my updated avatar.