ANTI-SPAM
-Akismet
Akismet checks your comments against the Akismet web service to see if they look like spam or not.
So useful it comes bundled with WP out the box.
-Bad Behavior
Bad Behavior is a PHP-based solution for blocking link spam and the robots which deliver it.
I dunno how it works but it does.
-SABRE
Simple Anti Bot Registration Engine
Helps to setup CAPTCHA forms to stop those pesky spambots from signing up. Very useful if you have a login form in clear view on your site.
USER BASED
-Dashboard Widget Remover
Easily remove any/all of the default WordPress dashboard widgets for specific user role. Useful for multi-user blog.
Have people logging in? Don’t want them to fiddle with loads of settings on the dashboard?
-WP Hide Dashboard
A simple plugin that removes the Dashboard menu, the Tools menu, the Personal Options section and the Help link on the Profile page, and prevents Dashboard access to users assigned to the Subscriber role.
This one just allows subscribers to access their own profile section and nothing else.
-Peter’s Login Redirect
Redirect users to different locations after logging in.
Allows you to point people to custom pages or to a specific area once logged in.
-Sidebar Login
Adds a sidebar widget to let users login
If you don’t want to point people to the WP admin login then this gives you a login form on the page.
-ThreeWP LoginTracker
Keeps track of all login and login attempts.
I know when you logged in…
-User Access Manager
Manage the access to your posts, pages, categories and files.
A wonderful plugin which locks or hides pages from people without the correct level of access.
STRUCTURE
-pageMash
Allows quick sorting, hiding and organising of parenting.
I hated the pages setup on WP and pagemash helps my poor little brain sort it out via a drag and drop style.
-Inline Posts
Allows you to include posts in pages (and in other posts).
This lets you create pages based on your blog posts. Useful to build pages with existing content AKA being lazy :p
-Inventory Manager
This plugin allows you to manage an inventory of products and display them.
I stumbled onto this while looking for a non transactional shopping plugin and its dead easy to setup. The demo on the designers site uses cars for an example but its just as easy to use for one off custom items.
-Twitter Tools
A complete integration between your WordPress blog and Twitter. Bring your tweets into your blog and pass your blog posts to Twitter. Show your tweets in your sidebar, and post tweets from your WordPress admin.
I can’t really expand on this. If you use twitter, these tools are bloody vital and it contains Bit.ly URLs, Exclude Category and Hashtags
MISC
Being lazy I haven’t grouped these beyond this hodgepodge.
-del.icio.us for WordPress
Displays your recently listened links.
Because I don’t use delicious anymore.
-Google Analytics for WordPress
This plugin makes it simple to add Google Analytics to your WordPress blog
I’m watching you…
-Google XML Sitemaps with Multisite support
Improved Google XML Sitemaps plugin with Multisite Support
Because you can never have enough snake oil.