SEO
-Google XML Sitemaps | This plugin will generate a special XML sitemap which will help search engines to better index your blog. | http://wordpress.org/extend/plugins/google-sitemap-generator/
-Breadcrumb NavXT | Breadcrumb NavXT, the successor to the popular WordPress plugin Breadcrumb Navigation XT, was written from the ground up to be better than its ancestor. This plugin generates locational breadcrumb trails for your WordPress powered blog or website. These breadcrumb trails are highly customizable to suit the needs of just about any website running WordPress. | http://wordpress.org/extend/plugins/breadcrumb-navxt/
-Yet Another Related Posts Plugin | Yet Another Related Posts Plugin (YARPP) gives you a list of posts and/or pages related to the current entry, introducing the reader to other relevant content on your site. | http://wordpress.org/extend/plugins/yet-another-related-posts-plugin/
-Platinum SEO Pack | Platinum SEO Plugin offers Complete onsite SEO solution for your Wordpress blog.Platinum SEO Plugin offers all the functionalities of All In One SEO plus more cooler onsite SEO options. It is automatic and also imports all your current settings in All in one SEO Plugin.But you need to disable All In One SEO before enabling Platinum SEO. | http://wordpress.org/extend/plugins/search.php?q=Platinum+SEO+Pack
-Missing Data Platinum SEO Pack Plugin, Add-on | A plugin which generates a list of all posts and pages where data pertaining to the PSP plugin is missing. Such as title, description and keywords. | http://wordpress.org/extend/plugins/missing-data-platinum-seo-pack/
-SEO Friendly Images | SEO Friendly Images automatically adds alt and title attributes to all your images. Improves traffic from search engines and makes the image tags W3C/ | http://wordpress.org/extend/plugins/seo-image/
-SEO-Tool - Keyword Density Checker | This SEO-Tool provides a keyword analyzer calculating the keyword density of the page/post content and generating statistics for keywords and phrases. | http://wordpress.org/extend/plugins/seo-tool-keyword-density-checker/
-SEO Smart Links | SEO Smart Links provides automatic SEO benefits for your site in addition to custom keyword lists, nofollow and much more. | http://wordpress.org/extend/plugins/seo-automatic-links/
-SEO SearchTerms Tagging 2 | Multiply blog traffic by strengthening on page SEO, increasing the number of indexed pages, auto convert search terms into post tags, and more. | http://wordpress.org/extend/plugins/searchterms-tagging-2/
-Category SEO Meta Tags | Add ability to add meta tags for category and tag pages. This plugin specially designed to work with All In One SEO plugin. | http://wordpress.org/extend/plugins/category-seo-meta-tags/
-WordPress.com Popular Posts | This plugin can show the most popular articles in your sidebar, using data collected by Jetpack or WordPress.com Stats plugins. | http://wordpress.org/extend/plugins/wordpresscom-popular-posts/

Statistics
-WP-Piwik | Adds the piwik code to the footer and stats to the dashboard | http://wordpress.org/extend/plugins/wp-piwik/
-Piwik Analytics | This plugin adds the Piwik Web Analytics javascript code into the footer of your website. It has several useful options. | http://wordpress.org/extend/plugins/piwik-analytics/
-WordPress.com Stats | You can have simple, concise stats with no additional load on your server by plugging into WordPress.com's stat system. | http://wordpress.org/extend/plugins/stats/
-WP-Stats-Dashboard | Display your blog's stats graph plus your blog traffic, social engagement and social influence directly in your dashboard. See how you're ranking on Alexa, check out your Technorati authority, monitor your ranking across multiple sites and much more. | http://wordpress.org/extend/plugins/wp-stats-dashboard/
-Search Meter | Search Meter tracks what your readers are searching for on your blog. View full details of recent searches or stats for the last day, week or month. | http://wordpress.org/extend/plugins/search-meter/

Security and AntiSpam
-Wordpress Firewall 2 | This WordPress plugin monitors web requests to identify and stop the most obvious attacks. | http://wordpress.org/extend/plugins/wordpress-firewall-2/
-Growmap Anti Spambot Plugin | Defeat automated spambots by adding a client side generated checkbox asking the comment author to confirm that they are not a spammer. | http://wordpress.org/extend/plugins/growmap-anti-spambot-plugin/
-Simple Trackback Validation | Performs a simple but very effective test on all incoming trackbacks in order to stop trackback spam. | http://wordpress.org/extend/plugins/simple-trackback-validation/
-WP-DBManager | Allows you to optimize database, repair database, backup database, restore database, delete backup database , drop/empty tables and run selected queries. Supports automatic scheduling of backing up and optimizing of database. | http://wordpress.org/extend/plugins/wp-dbmanager/
-Login LockDown | Limits the number of login attempts from a given IP range within a certain time period. | http://wordpress.org/extend/plugins/login-lockdown/

Performance
-W3 Total Cache | Easily optimize the speed and user experience of your site with caching: browser, page, object, database, minify and content delivery network support. | http://wordpress.org/extend/plugins/w3-total-cache/
-WP Smush.it | Reduce image file sizes and improve performance using the Smush.it API within WordPress. | http://wordpress.org/extend/plugins/wp-smushit/

Writing
-Add Post Footer | Add Post Footer automatically add any custom paragraph, html code, ad code, technorati tags and/or related links list to the end of every posts. | http://wordpress.org/extend/plugins/add-post-footer/
-TinyMCE Advanced | Enables the advanced features of TinyMCE, the WordPress WYSIWYG editor. | http://wordpress.org/extend/plugins/tinymce-advanced/
-Easy Privacy Policy | Easy Privacy policy lets you quickly set up a google adsense compliant privacy policy for your blog with only a few clicks. | http://wordpress.org/extend/plugins/easy-privacy-policy/
-Insights | Insights allows you to quickly access and insert information|links, images, videos, maps...) into your blog posts. | http://wordpress.org/extend/plugins/insights/

Administration
-No Self Pings | Keeps WordPress from sending pings to your own site. | http://wordpress.org/extend/plugins/no-self-ping/
-ManageWP - Worker | ManageWP Worker plugin allows you to remotely manage your blogs from one dashboard. | http://wordpress.org/extend/plugins/worker/
-Plugin Central | Dashboard plugin update notification, update all plugins at once, move your plugins from one blog to another with plugin install. | http://wordpress.org/extend/plugins/plugin-central/

Monetization
-Pretty Link Lite | Shrink, track and share any URL on the Internet from your WordPress website. Create short links suitable for Twitter using your own domain name! | http://wordpress.org/extend/plugins/pretty-link/
-Adwit Banner Manager | Insert ad spots into your blog and sidebar in one click! ABM is a very simple and powerful ad manager with exclusive optimization tools. | http://wordpress.org/extend/plugins/adwit-banner-manager/
-AdSense Integrator | AdSense Integrator plugin represents a simple and powerful solution to add and manage AdSense and other non Adsense ads, custom or similar to Adsense, into your blog | http://wordpress.org/extend/plugins/adsense-integrator/
-WP Super Popup | Creates unblockable, dynamic and fully configurable popups for your blog. It works also if WP Super Cache or W3 Total Cache is enabled! | http://wordpress.org/extend/plugins/wp-super-popup/
-WordPress ClickBank Plugin | This is a fully automated and smart ClickBank affiliate plugin for WordPress. | http://wordpress.org/extend/plugins/wordpress-clickbank-plugin/
-WordPress Clickbank Integration | An easy to use WordPress plugin to integrate with Clickbank. | http://wordpress.org/extend/plugins/wordpress-clickbank-integration/
-WP ClickBank Ad Display | This plugin creates an widget to display ClickBank keyword sensitive ad on your wordpress blog | http://wordpress.org/extend/plugins/wp-clickbank-ad-display/
-Donation Widget | More than just a button - includes progress meter and photo - available in 3 sizes and 9 colors. | http://wordpress.org/extend/plugins/donation-widget/

Membership, Autoresponder, List Building
-Newsletter Sign-Up | Adds a checkbox to your comment form that allows people to subscribe to your newsletter. Turn your commenters into subscribers! | http://wordpress.org/extend/plugins/newsletter-sign-up/
-SS Downloads | Embed forms in your pages and posts that accept an email address in exchange for a file download. | http://wordpress.org/extend/plugins/ss-downloads/screenshots/
-s2Member | s2Member is an extremely powerful (and free) membership management system for WordPress®. s2Member integrates seamlessly with PayPal® (very easy). | http://wordpress.org/extend/plugins/s2member/
-WP Autoresponder And Newsletter Plugin | With WP Responder you can create email newsletters, follow up autoresponders and provide subscription to blog via e-mail. | http://wordpress.org/extend/plugins/wp-responder-email-autoresponder-and-newsletter-plugin/

Reviews
-WP Customer Reviews | WP Customer Reviews allows your customers and visitors to leave reviews or testimonials of your services. Reviews are Microformat enabled (hReview). | http://wordpress.org/extend/plugins/wp-customer-reviews/
-GD Star Rating | GD Star Rating plugin allows you to set up rating and review system for posts, pages and comments in your blog. You can set many options for displaying the rating stars, and add widgets into the sidebars for displaying top ratings and other statistics generated by the plugin. | http://wordpress.org/extend/plugins/gd-star-rating/
-Xavin's Review Ratings | Adds a shortcode tag [xrr rating=4/5] that displays a rating in one of several formats. Intended for sites doing reviews. | http://wordpress.org/extend/plugins/xavins-review-ratings/

Frontend
-Contact Form 7 | Contact Form 7 can manage multiple contact forms, plus you can customize the form and the mail contents flexibly with simple markup. The form supports Ajax-powered submitting, CAPTCHA, Akismet spam filtering and so on. | http://wordpress.org/extend/plugins/contact-form-7/
-Subscribe to Comments Reloaded | Subscribe to Comments Reloaded allows commenters to sign up for e-mail notifications of subsequent replies. | http://wordpress.org/extend/plugins/subscribe-to-comments-reloaded/
-TPG Get Posts | Adds a shortcode tag [tpg_get_posts] to display posts within any static page or post.  Posts can be selected by tags or categories.

User Integration and Social Media
-WP-Polls | WP-Polls is extremely customizable via templates and css styles and there are tons of options for you to choose to ensure that WP-Polls runs the way you wanted. It now supports multiple selection of answers.
-Comment Redirect | Redirect commenters who just made their first comment to a page of your choice.
-Crossposterous | WordPress to Posterous cross-posting plugin.
-AddThis | The AddThis Social Bookmarking Widget allows any visitor to bookmark and share your site easily with many popular services.
-FeedBurner Subscription Widget (English) | Feedburner Subscription Widget is a WordPress plugin that let you insert a widget feedburner email subscription form in your widgeted sidebar.