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.
Debug Bar
Places a button in your admin bar that gives you troubleshooting information for each page that you are on, including PHP Errors, SQL queries, HTTP Requests and a full server rundown. Develop WordPress sites faster and more efficiently, with all of your debugging info in one place.
Quick Page/Post Redirect
Add redirects to your site, either on a post by post basis using a metabox provided at the bottom of your post editor, or using the Quick 301 Redirects feature for any page or directory. Global override options are also available and customizable.
Relevanssi
Improves search automatically by building a more comprehensive index then WordPress out of the box. Options to customize what gets included in the index, caching options, and fine-tuned control, and works with existing search forms.