There are a few plugins I would like to suggest to anyone who has WordPress installed: 

Akismet
URL:  http://wordpress.org/extend/plugins/akismet/ 
Description: This plugin fights spam. What it does it takes any comments you might have and matches them to a server, if one of them matches a known spammer then it gets tagged as such, and doesn’t appear on your blog. If a comment was tagged as spam in error it gives you the option to publish it regardless. Akismet requires a WordPress.com API key. Just sign up for a username on WordPress.com and copy the key down, then when prompted in the installation process enter the key. 

All in One SEO Pack
URL:  http://wordpress.org/extend/plugins/all-in-one-seo-pack/
Description: This plugin optimizes your blog for SEO (search engine optimization). It allows you to update the meta details exactly how you want them for either the entire blog, or specific pages. 

Google XML Sitemaps
URL:  http://wordpress.org/extend/plugins/google-sitemap-generator/
Description: This plugin will create a Google sitemaps compliant XML-Sitemap of your blog. The reason to use this plugin is to allow easier indexing of your site. Google’s bots love it. 

WordPress.com Stats
URL: http://wordpress.org/extend/plugins/stats/ 
Description: This plugin tracks users to your blog. Its sort of like Google Analytics, which I noticed you use, but specifically for wordpress. It gives you the search engine keywords and tracks any clicks users might make. Wordpress.com Stats uses the WordPress.com API too. 

WP-Polls
URL: http://wordpress.org/extend/plugins/wp-polls/
Description: This plugin gives you the ability to add polls to your posts. A nice interactive feature that I like to occasionally use. 

Subscribe2
URL: http://wordpress.org/extend/plugins/subscribe2/
Description: Allows users to enter their email address, then whenever your blog is updated they will receive an email telling them of the new activity. 

Sociable
URL: http://wordpress.org/extend/plugins/sociable/
Description: What this plugin does is it adds the icons to social network at either the top or bottom of the post. Users of your blog can click on these links to bookmark your post on sites like Digg, StumbleUpon, and more. You can also choose which networks you want displayed.