The Admin Menu plugin for WordPress makes key areas of the admin menu available from your site's front end when you're logged in.
The Article Uploader plugin for WordPress lets you upload your post and page content as files, and disable WordPress' text formatting features for individual entries. (Premium)
The Autolink URI WordPress plugin automatically converts urls to hyperlinked urls.
The Autotag plugin for WordPress leverages Yahoo's web services to automatically assign tags to your posts and pages. (Premium)
The Dealdotcom plugin for WordPress creates widgets that let you display Dealdotcom's deal of the day on your site.
The Do Follow plugin removes the nofollow attribute that WordPress adds in comments.
The Fancy Excerpt plugin for WordPress is a sentence-aware excerpt generator.
The Feed Widgets plugin for WordPress lets you insert any widget into your RSS feed. (Premium)
The Frame Buster plugin for WordPress will thwarts attempts to serve your web site from within a frame.
The HitsLink plugin for WordPress adds HitsLink support to your site.
The Mediacaster plugin for WordPress lets you manage a variety of podcast formats, including audio files, flash videos and iPod videos, as well as file downloads and YouTube videos. (Premium)
The Newsletter Manager plugin for WordPress lets you easily integrate third party newsletter managers such as aweber, getresponse, or 1shoppingcart. (Premium)
The Opt-In Front Page plugin for WordPress lets you select posts that show on your front page, allowing you to set up additional "Asides" feeds as you see fit.
The Search Reloaded plugin for WordPress leverages MySQL's full text indexing features to improve the WordPress' built-in search feature. (Premium)
The Semiologic Affiliate plugin for WordPress lets you automatically add your affiliate ID to links to semiologic.com and getsemiologic.com.
The Semiologic Cloner plugin for WordPress lets you clone a WordPress or Semiologic Pro site's preferences. (Premium)
The Subscribe Me Wordpress Plugin lets you display RSS subscription buttons to services such as Feedly or Bloglines.
*Retired * - Unfancy Quote is a WordPress plugin that disables WordPress' curly quotes feature, which is at times buggy and which invariably breaks code snippets.
Retired - The Uploads Folder wordPress plugin changes your uploads folders to something more natural, based on the post's date rather than the current date, or the static page's position in the hierarchy.