These 12 Plugins are the most useful for any WordPress Blog. These all are being used in our blog and will surely help you in making your blog best.
Commentluv – Plugin to show a link to the last post from the commenters blog in their comment. Just activate and it’s ready. Will parse a feed from most sites that have a feed location specified in its head html.
FeedBurner FeedSmith – This plugin detects all ways to access your original WordPress feeds and redirects them to your FeedBurner feed so you can track every possible subscriber. By FeedBurner.
Google XML Sitemaps – This plugin will generate a sitemaps.org compatible sitemap of your WordPress blog which is supported by Ask.com, Google, MSN Search and YAHOO.
WordPress Database Backup – On-demand backup of your WordPress database. Navigate to Manage ? Backup to get started.
All in One SEO Pack – Out-of-the-box SEO for your WordPress blog.
WP Super Cache – An extremely efficient WordPress page caching system to make your site much faster and responsive. It works by caching WordPress pages and storing them in a static file for serving future requests.
All in One Adsense and YPN – This plugin easily and automatically inserts Adsense or YPN code in to your blog posts. Ad position can be random or pre-defined. Configure options also available.
Social Bookmarking Widget – Help your visitor promote your website or blog. Put the AddThis Social Bookmarking Widget on your site or blog, so any visitor can easily bookmark it. The widget works with all popular bookmarking services.
WordPress Automatic Upgrade – It allows a user to automatically upgrade the wordpress installation to the latest one provided by wordpress.org using the 5 steps provided in the wordpress upgrade instructions.
Related Posts – Generate a related posts list via tags of WordPress.
Top Commentators Widget – Adds a sidebar widget to show the top commentators in your WP site. Adapted from Show Top Commentators plugin.
WP AJAX Edit Comments – Allows you and your users to edit their comments inline. Admin and editors can edit all comments.
Please do comment about more plugins if I have missed any.