The LDAP plugin provides authentication through one or more LDAP servers.
The Akismet plugin for b2evolution checks feedback through a central service ( http://akismet.com ) against spaminess.
Do you have many files/images in your media folder? When you hit the "files" button it takes a long time to load as it loads all the files/images in the folder. What if you have a few hundreds of files...
This plugin provides a button for quick and easy files upload.
Replace a standard search widget with Advance Search and you will be able to filter results by many parameters ( blog, category, post author ) plus you can customize almost everything.
The Avatars Plugin allows you to attach avatars (display pictures, gravatars, profile pics, etc) to a user, blog, and category. You upload avatars within the b2evo administration, with either a large or small (or both) avatar images. If a large avatar image is specified then lightbox functionality is seen, as when the user clicks the small avatar, the large avatar will show in a lightbox.