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All in One SEO Pack This plugin enables certain modifications to your Wordpress blog to achieve Search Engine Optimization. For example, you can customize your post title, post description and post tags for individual post. Furthermore, this plugin also has features such as auto generates Cononical URLS for your entire Wordpress site and select index/noindex for various archives pages.
This plugin will monitors links in your site and list out links that don’t work or any missing images. The reason why this plugin is essential is because you may write an article and link to www.domain.com. This link may goes down in future and become dead ends for search engine. By using this plugin, you can get notifications immediately and remove these dead ends.
This plugin will create a Google sitemaps compliant XML-Sitemap of your WordPress blog. A sitemap will help search engine spiders to crawl your content. The generated sitemap also supported by other search engine such as Yahoo, MSN and Ask.com.
SEO Friendly Images is a Wordpress optimization plugin which automatically updates all images with proper alt and title attributes. By having a proper alt and title tag for your images, you can get more traffic from Google Image Search. This blog had gain quite a large number of traffic from Google Image Search by doing so.
Although internal linking in your own site help navigate user to your posts, but it actually decrease your page rank because of the self pings effect. This plugin will eliminate this effect by removing all pingbacks from own site and only receive back links from other sites.
One of the important search engine fact is that search engines will treat www.domain.com and domain.com as two different site. You can easily overcome this issue by enforcing this plugin. Note: All in One SEO Pack will overcome this issue for you. Make sure you check the Canonical option.
This plugin covers all the features of All in One SEO Pack, but it does include more options compare to All in One SEO Pack. For example, it adds index, noindex, follow or nofollow, noodp, noydir, noarchive, and nosnippet meta tags to any post/page. But, most of my clients prefer All in One SEO Pack as they are used to it and reluctant to change.
SEO Smart Links can automatically link keywords and phrases in your posts and comments with corresponding posts, pages, categories and tags on your posts. This will help navigating your visitors to other posts. The interlinking process happens automatically and what you need to do is configure it through the administration settings panel.
Long URL may have a better ranking in search engines because it will contain more keywords. But search engines like Google tends to ignore some common keywords such as “you”, “a”, “the”, and “what”. Removing these keywords will improve your search engine ranking. This plugin will automatically remove these unused common keywords for you.
Robots Meta enables users to control which pages/posts can be indexed and which can’t. For example, you may want to prevent indexing of your search results or your category pages. It is because some search engines will see them as duplicate content and decrease your page rank.
AdRotate add and manage the code from the dashboard and show a random banner, or multiple, on your site. The plugin supports groups for banners allowing the different sizes to show up where they fit and not a vertical banner in the content or header and so on. Easy management from the dashboard allows you to quickly oversee, add and edit banner code. 
