Wordpress is immensely powerful straight out of the box, but it's possible to add pretty much ANY functionality you want, and it's usually for free.
This is a list of the TOP Plugins we use at q292u.com.
They are in no particular order.
(This is an UPDATED version of an earlier post. There are SIGNIFICANT changes, as Wordpress is such a moving target)
ESSENTIAL anti-spam system. Free to non-commercial users.
Filters out unwanted (spam) comments automatically, and provides stats on what it's doing. ESSENTIAL.
This one is essentially a multi-plugin. It gives you a lot of the functionality of Wordpress.Com. You can do away with all the social bookmarking button plugins, contact form plugins, "Follow Me" plugins, and much more. ESSENTIAL. You need a (free) wordpress.com account.
FEEDBURNER FEEDSMITH.Redirects all RSS feeds to your Feedburner feeds. So you can control all RSS activity. From there you can do e-mail Subscriptions and much more.
Including automatic TWITTER integration! Get a feedburner account. ESSENTIAL.
Handles ALL aspects of SEO (Search Engine Optimisation). Options to rewrite article titles, handles Keywords, meta tags, everything. There's also a "PRO version. You won't need it. ESSENTIAL.
Handles advertising on your site. Very comprehensive. Individual ads are created and then made into groups. You can then position the groups as widgets, in posts and on pages. Ads have start and end dates, and tracking can be switched on or off. Better than maxbannerads. STRONGLY RECOMMENDED
WP AUTO TAGGER.
Automatically adds relevant tags to your posts as you create them, based on post content. It'll find tags you hadn't thought of. STRONGLY RECOMMENDED.
Add relevant eBay listings to your posts and pages. This plugin is NOT free, but it's worth the money. Simply set it up, and use shortcodes to position ads. Now includes a widget as well. RECOMMENDED.
Automatically creates posts on your blog, based on predefined RSS feeds. Excellent. RECOMMENDED.
Excellent caching plugin, creates static version of all your posts and pages as they are created. Far better than SUPERCACHE. ESSENTIAL if you use a lot of plugins, or have a lot of visitors.
Get the "Clear Cache" Button plugin as well.
EXCLUDE FROM NAVIGATION.
Some themes automatically add all pages to navigation menus. This is how to stop it. Adds a checkbox in the editor. ESSENTIAL.
GOOGLE XML SITEMAPS.
Automatically generates and submits sitemaps to Google. You can also submit these to Yahoo and Bing, yourself. Helps with SEO. ESSENTIAL.
Automatically create scheduled database backups and e-mail to yourself.
Simple and effective. ESSENTIAL.
Attempts to redirect 404 errors to relevant pages based on search query, and URL requested. Reduces bounce-rates. ESSENTIAL
Simply changes the return e-mail address for automatically-generated e-mail messages to something like "NOREPLY@domain.com". ESSENTIAL.
This adds Google Analytics tracking code to all your pages and posts, so you can keep tabs on everything. You need an analytics account. ESSENTIAL.
CONTEXTUAL RELATED POSTS.
Adds links to other relevant posts on your site. Engages visitors, and keeps them on your site longer. STRONGLY RECOMMENDED.