SnapperTalk

One of the best reasons to use WordPress to run your blog is the massive range of plugins you can add to enhance its functionality. Here’s my list of the best:

Administration:

Fluency Admin – cleans up the whole admin interface
Admin drop down menu – add’s drop down menus to the Admin pages and is compatible with Fluency Admin
One Click Plugin Updater – get notified of plugin updates, do them all in one click, and install plugins in one click without needing to FTP them using the OneClick Installer for Wordpress FireFox add-on
WP Enhanced Plugin Manager – adds additional functionality for upgrading plugins
WordPress Automatic Upgrade – Massive timesaver letting you upgrade WP installation to latest version semi-automatically
WP Super Cache – static caching to reduce load on your server
WordPress Database Backup – easily back up your WP database

Security & Anti-Spam

Spam Karma 2 – Essential plugin to prevent against comment spam. The alternative is Akismet which is bundled by default on new WP installations but which is inferior in my opinion.
SABRE – Adds measures to stop spambots registering as users of your site
Bad Behaviour – adds some security measures to prevent against spam and other malicious attacks
WP Security Scan – scans your WP installation to look for security holes
Hotlink Protection – Prevents other websites from hotlinking to images on your site
©Feed – Adds a copyright notice and digital fingerprint to the end of each post when seen in RSS feeds, enabling you to see who is stealing your content
Easy Contact – Adds an anti-spam contact form for readers to send you a message without revealing your email address

Search

All in One SEO Pack – automatically optimizes your site to be more search engine-friendly
Google (XML) Sitemaps Generator – automatically generates an XML-Sitemap to allow search engines to more effectively catalog your site
Search Everything – Customise exactly which pages, posts, categories etc are seen by the internal site search

Statistics

Ultimate Google Analytics – enables you view all your site’s statistics using Google Analytics
WordPress.com Stats – A pretty decent statistics package though requires (free) signup at www.wordpress.com if your blog is self-hosted.

Misc

WordPress Mobile Edition – automatically detects if the reader is using a handheld device or phone, and reformats your site for optimal viewing
Subscribe to Comments – allows commenters on your blog to check a box before commenting and get e-mail notification of further comments

You can find more WordPress plugins here