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.

A new trend in spam is to duplicate legit comments from your readers to hopefully pass spam filters. Spammers post content that was previously approved on your site, but with their own name and URL. This plugin prevents this.

Ozh' No Duplicate Comments

Prevents spammers from duplicating legit comments but with their commenter name and URL

Ozh' Avatar Popup vs Ozh' No Duplicate Comments