Here is the list of top rated SEO wordpress plugin. which will help to boost your search engine ranking within very short time.

All in One SEO Pack – One of the most popular plugins of all time for WordPress, this plugin SEO swiss army knife from helping choose the best post title and keywords, to helping you avoid duplicate content and more. If your running Thesis this may be a little redundant as it handles alot of the same features. (This WILL conflict with Meta Robots and Headspace.)
Redirection – For any number of reasons you sometimes need to move a page from one spot on your blog to another, but if not done correctly you risk losing that pages status in search results.  The Redirection plugin saves you time and headaches with 301 redirects, it captures a log of 404 errors so you can work on correcting them, and sets up an RSS feed for errors.

Automatic SEO Links – Ever looked up from Wikipedia and realize you’ve been reading for like an hour that is because of their thorough interlinking between articles. Interlinking has two benefits it will spread link juice deeper into your site, and also it will make your site more sticky as users more easily can find key content. Automatic SEO Links allows you to choose a word or phrase for automatic linking, both internal and external, set anchor text, and choose if it should be “nofollow” or not.  One of the best features of this plugin is that it will only do this for the first occurrence of a word in a post so you don’t look like your just spamming.

SEO Smart Links – This SEO-friendly plugin can automatically link keywords and phrases to related comments, posts, pages, and categories within your site. This makes less prominent pages or older content more relevant and crawl-able for search engines, and keeps site visitors engaged. It also lets you set “nofollow” tags on URL’s and create custom keyword lists with automated URL hyperlinks for individual terms.
I Love Social Bookmarking –  I.L.S.B. is a great way to encourage blog readers to rank your post on popular social media sites.  In the past year, sites like Digg, Delicious, StumbleUpon, and Sphinn have become major resources for driving relevant traffic to quality site content.  This plug in inserts an attractive drop-down menu next to your blog posts that allows readers to submit or rank your site content on a number of popular social media sites, without leaving your blog.
WP to Twitter —Twitter is an ideal space for (viral) content sharing since users are constantly engaged in niche conversations.  Now that Google’s Social Search indexes tweets at the top of SERP’; more tweets/retweets = more indexing power.  WP to Twitter is a plugin that automatically tweets a tiny URL link to new blog posts or blog edits on your site.   Without any additional effort, your content is distributed to a relevant, willing audience; this can drive relevant traffic and increase your presence in social search results.
WP-Super-Cache —This plug in contributes to your site speed and it helps your blog load faster.  The number of pages on your blog that a search engine will index on a daily basis increases with speed.  If indexing each page is a quicker endeavor, more pages will be indexed.  WP-Super-Cache creates static html pages from your WordPress blog so your server will present this file instead of the much denser PHP script.  This will also help fortify your server when it is receiving a high amount of traffic, which can result from all your other great SEO strategies!  This is because this plug in serves a static html page to 99% of your site visitors.
Robots Meta — Robots Meta automatically inserts “nofollow” tags on internal site links that are irrelevant to search crawlers; this keeps search engines from wasting time indexing unimportant pages like results, login, and admin pages, instead directing crawlers to index primary site content.
SEO Slug — Blog post titles typically get an h1-h3 heading, which makes them very important in terms of keyword optimization.  SEOSlug optimizes blog post titles to improve search engine visibility by editing keyword strings. It removes conjunctions from titles, (words like “as” and “if”) to allow crawlers to more readily crawl main content keywords as a fluid string.
Social Traffic Monitor:Social Traffic Monitor is a plugin for WordPress blogs that monitors your blog traffic for activity coming from social news or bookmarking sites.
Facebook Social Widgets:Fully customizable widgets ( not just iframe includes ). Social plugins enable you to provide engaging social experiences to your users with the flexibility of widgets.
SocialGrid:It is a simple widget that makes it easy to add and organize links to your various profiles on the internet.
Social Media Page – Rather than just including all your social media links in the sidebar by default, the Social Media Page plugin, which supports approximately 140 social networks, allows you to include your social profiles on any page or post with a simple line of code. This is ideal if you want to link out to your profiles, without cluttering up your sidebar with lots of icons.
Social Profilr – With only 14 social networks to choose from, the Social Profilr plugin is far from all inclusive, however it has a nice twist. Most of these plugins only allow for the actual profile links. Social Profilr steps it up a notch by also letting you include a line of text (with or without HTML) as a brief introduction. In essence, you can turn this into a brief “About Me” or “About the Blog (” blurb with a link to your full WordPress “About” page. This appears above your social profile icons, which can be displayed in either vertical, horizontal or dropdown fomat.
Lifestream – More independent than the other options listed here, the Lifestream plugin doesn’t require a third party account in order to stream your social activity. Although out of the box, this plugin doesn’t have the best design (it’s more cluttered than the other two), its biggest benefit is that it gives you the option of being utilized as either a sidebar widget, or on a separate page/post of its own. Like the FriendFeed widget, it gives you the option of hiding Twitter @replies from your stream, too.
Retaggr – With more than 180 social networks to choose from, Retaggr is another great option for promoting your social profiles. This particular plugin is somewhat limiting, in that commenters need to have a Retaggr account in order for them to receive the extra link love from your site. But if they do, the plugin places a tiny icon next to their comment. Rolling your mouse over the icon pops up their profile information including their name and social media links.