Personalize, if not humanize, your posts, adding (CSS) popups containings avatars next to mailto links, as well as next to any word. You can chose avatar images, or let Gravatar chose it for you.
For documentation and tips, please refer to the official plugin page for <a href="http://planetozh.com/blog/my-projects/wordpress-plugin-avatar-gravatar-popup/" title="Avatar Popup" rel="nofollow ugc">Avatar Popup</a>

Ozh' Avatar Popup

Add CSS popups next to mailto links or next to any word. Can be any custom image, and has gravatar support.

Guesses your visitor’s Country from his IP. You can then add commenter’s nation flags next to their name in comments, for example.
For documentation and tips, please refer to the official plugin page for <a href="http://planetozh.com/blog/archives/2004/08/27/ip-to-nation-plugin/" title="IP to Nation" rel="nofollow ugc">IP to Nation</a>

Ozh's IP To Nation

Guesses your visitor's Country from his IP

Ozh' Avatar Popup vs Ozh's IP To Nation