I wrote this plugin a few months back, use it on all my sites, and finally got around to uploading it to the WordPress.org plugins repository this morning.
The plugin increases your users’ privacy by hiding Profile Pictures (Gravatars) from logged out users (and bots) visiting your site.
It also allows individual registered users on the site to choose whether or not they have a Gravatar displayed for them in their User Profile settings.
Why is this important? Primarily because the “hash” that Gravatar uses to retrieve and display your picture can be used to find other places on the web where you have provided comments or posts and could even be used to reveal your email address in some cases – here’s a good in-depth article by Wordfence on the risks.