It's a gravatar. A gravatar, or globally recognized avatar, is quite simply an avatar image that follows you from blog to blog appearing beside your name when you comment on gravatar enabled sites, which Geeks in Phoenix and StGelais.com are. Avatars help identify your posts on web forums, so why not on blogs?
For more information about gravatars, click here
http://en.gravatar.com
To sign up for one, click here
http://en.gravatar.com/site/signup