There are thousands of plugins for WordPress, but you should have a list of “core” plugins that you use in most installations.  Here are a few of the most useful ones I’ve found that typically end up using  because they’re just too darn useful. Feel free to mention your favorites below in the Comments.

This is a running list, I’ll be back to edit it from time to time:

1)      All in One SEO – This plugin gives you a lot of control over impotant SEO page elements and features WordPress does not include by default, including:  Custom homepage title and description, custom page and post META content (titles/descriptions/keywords), optional dynamic titles and descriptions for posts, pages.  Far too useful to pass up, even if you’re only using it 50% of the time.  Get it now!

2)      NextGen Gallery – This has come in handy if you want to run image galleries. NetGen gallery gives you a relatively simple and consistent interface for posting and managing lots of photos and image galleries.  It’s customizable and despite a few nuances not worth mentioning, it’s quite stable.  Get it now!

3)      Google XML Sitemaps – I hate dealing messing with Sitemaps, and this plugin automatically builds them and makes sure Google has the latest version of your Sitemap. Get it now!

4)      PageMash – Allows you to drag-and-drop page ordering and sub-pages as well as hide any pages from the Navigation you don’t want to appear.  Very useful for sites that need a lot of Page content. Get it now!

5)      Statpress (Reloaded and SEOlution) – If you don’t mind making your database a little heavy (which Statpress will do), it’s a nice built-in analytics program.  There are multiple versions of StatPress, but with any of them you’ll get built-in analytics of recent Searches, spiders, visitors, pageviews, etc.  Get it now!

6)      Google Analyticator – I was a fan of Ultimate Google Analytics until I discovered this one, which uses the new Google Asyncronous code providing Event tracking, faster loading and some new features.  You can very easily add Google Analytics to your blog without even knowing the site’s UID.  It also gives you a handy Dashboard widget for quick stats, download link tracking, and hides visits from the site admin. If you’re using Google Analytics with this plugin, you probably won’t have much need the bulky Statpress mentioned above.  Get it now!

7)      Cookies for Comments – This one was recently given to me by a friend on Facebook as a way to keep Spam bots from posting random crap comments to your site.  It creates a stylesheet that drops a cookie when a browser loads it.  If the cookie isn’t found, a comment cannot be created.  Good to stop spam before it even starts.  If Akismet isn’t doing the trick, try this one. Get it now!

8)      CForms II – Quickly build submission forms for users to send you data.  Perfect for sites generating leads, or even just general contact forms.  Comes with a bunch of built-in themes, and with a little CSS tweaking, can integrate nicely into any Website. *cFroms has been depreciated since this was written.*

9)      Breadcrumb NavXT – Easily add breadcrumb trails to your WordPress site.  Breadcrumb trails are good for navigation and site usability, as well as useful for SEO.  Get it now!

A couple more great WordPress Plugins to mention:

Shopp – If you want to run an E-commerce store on your blog, this is by far the best option.  I would recommend this if you’re running a store with less than 200 items for sale or managing inventory can get rather cumbersome.  Shopp is a “premium” plugin sold at $55 for a single store license or $299 for unlimited stores, and well worth the expense if you want an easy way to sell online.  I’ve tried the competition and I am convinced this easily takes the cake for the best out of the box E-commerce system for WordPress.  I’ll write more on running E-commerce blogs in the future. Get it now!

Advertising Manager – This is a great plugin if you’re running Adsense or ads from other online networks.  It will manage all of your Ads and Ad locations on the pages, create widgets, and allow for some internal customization.  See it for yourself:  Get it now!