Gravatar: Derived from ‘avatar’ – Globally Recognized Avatar, is basically an avatar image that follows you across the web when you comment on gravatar-enabled blogs using a unique e-mail address.
Interesting, because this would imply that anyone could use your gravatar if they knew the e-mail address you used to sign-up for the account. So if you’re going to sign up for one, I’d suggest using an e-mail address not known to anyone else.
If you have a blog of your own, take a look at the full implementation guide.
If you already have a wordpress blog, the easiest is to upgrade your installation to the latest available version (Version 2.5 comes with the functionality built-in – this only means gravatars will get more popular). Blogger hasn’t implemented it yet – although it should only be a matter of time before they do.
You might have to do some tweaking if you developed your own wordpress theme:
The syntax is:
function get_avatar( $id_or_email, $size = '64',$default = 'http://url-to-default-avatar' )
This example uses the user’s e-mail address to retrieve the gravatar at 80×80 pixels (add to comments.php):
<?php echo get_avatar( get_comment_author_email(), '80' ); ?>;