I have begun using gravatars. It is quite nice and makes my posts look more nicer. Furthermore, it is portable to any site that supports gravatars. For example, I can post a comment on the WordPress forums, and the picture shown will be what I choose for the gravatar. The same picture will be shown on any site that supports gravatars.
If a site does not support gravatars, it can easily get a plugin or add code to get gravatars working. The site is below and will give the details on how to get it working.
The WordPress plugin can be found here
The gravatar picture is not permanent. Apparently, if you change the gravatar, the picture will be updated on all sites that support it. I find this very nice.
If you are looking for a picture, you can do a search for avatar picture. I did a Google search for tux avatar to find mine.