Here a collection of  most downloaded wordpress plugins to use in your blog.

Akismet

Akismet checks your comments against the Akismet web service to see if they look like spam or not.

All in One SEO Pack

Automatically optimizes your Wordpress blog for Search Engines (Search Engine Optimization).

WP Super Cache

A very fast caching engine for WordPress that produces static html files.

Contact Form 7

Just another contact form plugin. Simple but flexible.

Sociable

Automatically add links on your posts, pages and RSS feed to your favorite social bookmarking sites.

Google Analytics for WordPress

The Google Analytics for WordPress plugin automatically tracks and segments all outbound links from within posts, comment author links

Google Analyticator

Adds the necessary JavaScript code to enable Google Analytics. Includes widgets for Analytics data display.

Google XML Sitemaps

This plugin will create a Google sitemaps compliant XML-Sitemap of your WordPress blog.

Page Flip Image Gallery

FlippingBook Wordpress Gallery plugin helps you to create Image Gallery with Page Flip effects on your blog.

NextGEN Gallery

NextGEN Gallery is a full integrated Image Gallery plugin for WordPress with a Flash slideshow option.

Plugin Manager

View, download and install plugins from WordPress.org Plugin Database from an AJAX’ed interface with a single click of the mouse.

Easy AdSense

Easy AdSense manages all aspects of Google AdSense for your blog: insert ads into posts and sidebar, and add a Google Search box. Easy and complete!

Smart YouTube

Smart Youtube plugin allows you to insert full featured YouTube videos into your post, comments and in RSS feed.

WordPress.com Stats

You can have simple, concise stats with no additional load on your server by plugging into WordPress.com’s stat system.

Random Pages Widget – For Visitors & SEO

Displays random posts and pages in sidebar. This increases the number of indexed pages and gives users an interesting way to browse your site.

Robots Meta

This plugin makes it easy to add the appropriate meta robots tags to your pages

WP-PageNavi

Adds a more advanced paging navigation your WordPress blog.

Add to Any: Share/Bookmark/Email Button

Help readers share, save, bookmark, and email your posts and pages using any service, such as Facebook, Twitter, Digg, Delicious and over 100 more.

WP e-Commerce

WP e-Commerce is a Web 2.0 application designed with usability, aesthetics, and presentation in mind.

Broken Link Checker

This plugin will check your posts, custom fields and the blogroll for broken links and missing images

FD Feedburner Plugin

Redirects the main feed and optionally the comments feed seamlessly and transparently to Feedburner.com.

WP-Polls

Adds an AJAX poll system to your WordPress blog. You can also easily add a poll into your WordPress’s blog post/page.

WP-Cumulus

WP-Cumulus displays your tags and/or categories in 3D by placing them on a rotating sphere.

Twitter Tools

Twitter Tools is a plugin that creates a complete integration between your WordPress blog and your Twitter account.

Twitter for Wordpress

Twitter for WordPress displays yours latest tweets in your WordPress blog.

Subscribe2

Sends a list of subscribers an email notification when new posts are published to your blog

WP-PostRatings

Adds an AJAX rating system for your WordPress blog’s post/page.

RSS Footer

This plugin makes it easy to add a line of content to the beginning or the end of all the articles in your feeds

WP-DB-Backup

On-demand backup of your WordPress database.

TinyMCE Advanced

Enables most of the advanced features of TinyMCE, the WordPress WYSIWYG editor.

GD Star Rating

GD Star Rating plugin allows you to set up advanced rating and review system for posts, pages and comments in your blog

WP-SpamFree Anti-Spam

Powerful anti-spam plugin that eliminates blog comment spam. Finally, you can enjoy a spam-free WordPress blog! Includes contact form.

Global Translator

Automatically translates your blog in 34 different languages!

WP-PostViews

Enables you to display how many times a post/page had been viewed.

WP Ajax Edit Comments

Allows users and admins to edit comments on a post. Users can edit their own comments for a limited time, while admins can edit all comments.

Tweet This

Adds a “Tweet This Post” link to every post and page, so your readers can share your blog entries on their Twitter accounts with ease.

Featured Content Gallery

Used to create a customizable rotating image gallery anywhere within your WordPress site.

Popularity Contest

This will enable ranking of your posts by popularity; using the behavior of your visitors to determine each post’s popularity.

Simple Tags

Simple Tags is the successor of Simple Tagging Plugin and is THE perfect tool to manage perfectly your WP

SI CAPTCHA for Wordpress

Adds CAPTCHA anti-spam methods to WordPress on the comment form, registration form, or both.

Lifestream

Streams your activity from over 50 different sources to your blog.

Sidebar Widgets

Adds “Sidebar Widgets” panel under Presentation menu

Pretty Link

Shrink, track and share any URL on the Internet from your WordPress website. Create short links suitable for Twitter using your own domain name!

WP-DBManager

Manages your WordPress database.

WP-Print

Displays a printable version of your WordPress blog’s post/page.

Redirection

Redirection is a WordPress plugin to manage 301 redirections and keep track of 404 errors without requiring knowledge of Apache .htaccess files.

WP Security Scan

Scans your WordPress installation for security vulnerabilities.

Exclude Pages

This plugin adds a checkbox, “include this page in menus”, uncheck this to exclude pages from the page navigation that users see on your site.

Scissors

Scissors enhances WordPress’ handling of images by introducing cropping, resizing, rotating, and watermarking functionality.

Theme My Login

Themes the WordPress login pages according to your theme.

Twitter Widget Pro

A widget that properly handles twitter feeds, including parsing @username, #hashtags, and URLs into links. Requires PHP5.

Viper’s Video Quicktags

Allows easy and XHTML valid posting of videos from various websites such as YouTube, DailyMotion, Vimeo, and more.

BuddyPress

BuddyPress is a suite of WordPress MU social networking plugins and themes.

SexyBookmarks

Adds an attractive social bookmarking menu to your posts, pages, index, or any combination of the three.

Wordbook

This plugin allows you to cross-post your blog posts to your Facebook Wall. Your Facebook “Boxes” tab will show your most recent blog posts.

WP-EMail

Allows people to recommend/send your WordPress blog’s post/page to a friend.

HeadSpace2 SEO

Controls almost every aspect of your site’s meta-data, including advanced tagging, Analytics, and dozens of plugins. The best WordPress SEO solution!

Lightbox Gallery

This plugin changes the view of galleries to the lightbox.

TweetMeme Button

Adds the TweetMeme button into your posts and RSS feed.

Wordpress Automatic upgrade

Wordpress automatic upgrade allows a user to automatically upgrade the wordpress installation to the latest one.

Category Posts Widget

Adds a widget that shows the most recent posts in a single category.

Sidebar Login

Adds a sidebar widget to let users login.

Really Simple CAPTCHA

Really Simple CAPTCHA is a CAPTCHA module intended to be called from other plugins. It is originally created for my Contact Form 7 plugin.

podPress

A dream plugin for Podcasters using WordPress..

Post videos and photo galleries

Post your videos and photo galleries/flash slideshows easily and in seconds.

wp-Typography

Improve your web typography with: hyphenation, space control, intelligent character replacement, and CSS hooks.

Advertising Manager

Easily place Google Adsense and other ads on your Wordpress blog. Simple to use, with powerful management and optimisation features.

NVoice

Your post’s in audio – The easiest way to create speech recordings.

PollDaddy

Create and manage PollDaddy polls from within WordPress.

Yoast Breadcrumbs

Easily add breadcrumbs to your template!