There are lot of Plugins for WordPress Blog’s but these are the basic plugins which is listed below for which every WordPress Blog should have. You can also search many other Plugins Here.
Akismet is such an plugin of which WordPress decided to package it with every new WordPress installation. It checks your comments against the Akismet web service to see if comments look like spam or not and lets you review the spam it catches under your blog’s “Comments” in Admin Dashboard.
Plugin Link : http://wordpress.org/extend/plugins/akismet
W3 Total Cache :
The fastest and most complete WordPress performance optimization plugin and it is trusted by many popular blogs. W3 Total Cache improves the user experience of your blog by improving your server performance, caching every aspect of your site, reducing the download time of your theme and providing transparent content delivery network (CDN) integration.
Plugin Link : http://wordpress.org/extend/plugins/w3-total-cache
Google XML Sitemaps :
This plugin will generate a special XML sitemap which will help search engines like Google, Bing, Yahoo and Ask.com to better index your blog. With such a sitemap, it’s much easier for the crawlers to see the complete structure of your site and retrieve it more efficiently.Additionally it notifies all major search engines every time you create a post about the new content.
All in one SEO Pack :
All in one SEO pack is a plugin which is must and should for any website or blog. You can fine-tune any of its settings if you wish. It works by giving you a unique title and meta tags for each page and post. You can override any title and set any META description and any META keywords you want.
Plugin Link : http://wordpress.org/extend/plugins/all-in-one-seo-pack
Google Analytics :
Plugin Link : http://wordpress.org/extend/plugins/googleanalytics
WP-DBManager is a WordPress Plugin which has a lot of capabilities and allows you to optimize your database, repair your database, backup your database, restore your database, delete your backup database , drop/empty tables and run selected queries. Supports automatic scheduling of backing up, optimizing and repairing of database.
Plugin Link : http://wordpress.org/extend/plugins/wp-dbmanager
Broken Link Checker :
Broken Link Checker is a plugin will monitor your blog looking for broken links and let you know if any are found. Monitors links in your posts, pages, comments, the blogroll, and custom fields. Detects links that don’t work, missing images and redirects. It notifies you either via the Dashboard or by email.
Plugin Link : http://wordpress.org/extend/plugins/broken-link-checker
Bing 404 :
Using the Bing Search library, this plugin will intercept your standard 404 page and return a list of urls that may help your user find the content they are looking for. You can limit the search to just the content on your site, set a default search in case the computed one doesn’t return any results, and set a host of other options, all designed to provide your users with quality recomendations.
Plugin Link : http://wordpress.org/extend/plugins/bing-404
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. It organically caches the related posts data as your site is visited, greatly improving performance. It also display’s related posts in your RSS and Atom feeds with custom display options.
Increase your audience engagement with innovative sharing tools!. The ShareThis plugin allows users to share your content through email and 50+ social networks including Facebook, Twitter, Digg, StumbleUpon and Reddit. By this plugin you can broadcast your message more easily and widely than ever before.
Plugin Link : http://wordpress.org/extend/plugins/share-this
This plugin will visit the site of the comment author while they type their comment and retrieve their last blog posts which they can choose to include at the bottom of their comment when they click submit. You will even be able to build your list/network/community even more by offering your readers the opportunity to register to your site to unlock advanced features of the plugin like being able to choose from any of their 10 last posts when they comment or other features like dofollow links and more.
Plugin Link : http://wordpress.org/extend/plugins/commentluv