VaultPress
Provides security for your WordPress site, scanning your install for vulnerabilities and fixing them automatically. It also backups your site several times a day, so that you can restore it with a click of a button.
User Switching
Adds new functionality in your admin panel so that you can switch between users and edit posts or profiles, then easily switch back at any time. Also allows you to Switch Off admin so that you can view site as a logged out user.
MailPoet Newsletters
Use a drag and drop interface to create and edit newsletters, either automatically recurring or one at a time. Pull in content from your WordPress install and customize the look and feel of your newsletter. Mobile friendly.
Ninja Forms
Create forms with a drag and drop interface, and then add them to your WordPress site with a shortcode or template tag. Several different field types are available, all completely customizable, with add-ons for extra functionality.
Post Status Menu Items
Add new menu items for each post status, with the number of posts in each, to your admin panel. Works with custom post types and custom post statuses, and fully customizable.
WP Super Cache
Cache pages using mod_rewrite or PHP automatically. There are lots of ways to customize the plugin, but the main appeal of this plugin is that static pages are created on the fly without having to set too much up.
Post Snippets
Add snippets of code or custom shortcodes by adding code samples in your admin panel. A basic templating language allows you to specify where variables should be inserted into code, and adds a button to TinyMCE to add snippets to posts.
Testimonials Widget
Add Testimonials to your site using a custom post type with specific custom fields. Testimonials can be added to WordPress using a shortcode, a built-in widget or template tags.
Theme-Check
If you are developing a WordPress theme, you need to make sure that your theme is compliant with the Theme Review Guidelines. This plugin automatically checks to make sure your theme is up to spec. in your admin panel.
Comments Not Replied To
Keep track of which comments have been replied to right from your admin panel. A new row will appear in your comments admin section that indicates whether or not it has been replied to, or it is from the post author.
Email Address Encoder
Automatically encode every email address in your posts and pages to protect it from spammers and attackers. Uses decimal and hexadecimal entities so there's no Javascript or extra code.
Meteor Slides
Add slideshows to your site using the jQuery cycle plugin. Pick from several different transitions, and organize slides into multiple slideshows. Add them to your posts or pages with a shortcode, function or widget.