These plugins go on 99% of the wordpress installs I do. I’ll only leave one off if there’s a very specific reason for it not to be there.
Akismet - This one actually comes with wordpress you only need to get a liscence to activate it. Unless you have need for spam in your blog this is one the most effective tools for stopping it. Very little actually gets through and very little gets flagged as a false positive.
Dagon Design Sitemap Generator - Let’s be honest once you’ve got a site over 50 pages maintaining a sitemap by hand is tedious and inefficient. This plugin has quite a few options and takes care of all the grunt work for you.
Organizer - This plugin allows you to create and upload files from the web browser without having to fire up your FTP program. It’s especially helpful on blogs with multiple users who aren’t tech savvy. The only downside is if they don’t know the “rules” things can get messy and disorgainzed very quickly.
Feedburner Replacement Plugin - Let’s you keep your feedburner feed on your domain.
Objection Redirection - This plugin by Dax is one of the most powerful and useful plugins I use. It let’s you redirect old and broken url’s to clean and fresh url’s without you having to touch an htaccess file.
Google Sitemaps The Google Sitemaps Webmaster Central program by Google is absolutely one of the most helpful things Google has ever put out. If you are fixing your own site or someone else’s there’s no better way to figure out what a search engine thinks about your site. This plugin updates and rebuilds the XML file everytime you make a new post and ping’s google to tell them about it. It’s especially helpful if you publish on a predetermined schedule. Warning make sure you have the file permissions set correctly or this won’t work properly.
Wordpress Database Backup - If there is one wordpress plugin you absolutely need this is it. It gives you the ability to backup the core database tables and any other tables you specify. The backups happen on demand or on a nightly schedule. While it might be against TOS what I do is set up a dedicated gmail account for each wordpress blog. I then set this plugin to backup the tables every night and email the file to a gmail account. Viola a free daily incremental offsite backup.
Permalink Redirect - In the event
some wise guy tries to mess up your blog this keeps things neat and tidy.
Highly Reccomended Plugins
These plugins go on most of my installs but not all of them
Search Pages - This plugin ties the built in search function in wordpress to the pages. The default installation only searches blog posts. This is an absolute neccesity if you are using wordpress as a CMS and not a blogging tool.
Search Meter - Looking at search logs to find out who’s searching for what can be a valuable tool for figuring out what’s right and what’s wrong on your site.
Static Homepage - If you want to use wordpres as a CMS instead of a blog this plugin makes the homepage magic happen.
Cool Stuff
Not necessary but sometimes pretty helpful
Adhesive - Allows you to stick a posting to the top overriding the standard chronological order of things.
Adsense Deluxe - A powerful way to control adsense from a master level on your blog.
Adsense Injection - Another Dax special that randomly inserts Adsense somewhere in each posting. Not advisable for the control freaks, definitely advisable for sites with lots of returning readers who don’t normally click on Adsense.
Bunny’s Technorati Tags - A simple and easy interface for tagging in each blog post.
Bread Crumb Trail Generator - A little tricky to configure but very useful once you do. Especially nice when used on a static website.
Feed Copyrighter - Let’s you add copyright info to your feed. Makes it easy to track and follow scrapers.
Moderate Trackbacks - Not used as much as it once was Akismet catches most of the spam, but I keep it around as a backup.
Postie - A very powerful tool if you do remote posting via email. Takes a little tinkering to get it set up right but once you do it’s hands off. Combine with cronless postie for regular automated checking.
Related Posts - Automagically creates a list of related posts.
Recent Posts and Recent Comments - Shockingly these two plugins give you a list of recent posts and recent comments, go figure.
Flickr Photosets - If you are doing anything with flickr this plugin kicks ass letting you tie it into your wordpress bog. Especially nice if you’ve upgraded to flickr pro and have multiple albums,
see an example.
Top 10 Posts - gives you the top 10 posts by views, very hackable see my
top 100 posts for an example.
WP Cron - Makes all sorts of wordpress housekeeping features happen automagically. Just be sure to activate the main plugin first before any of the others or things may not work properly.
WP - Admin Bar - Puts a really nice navigation bar up for users who are logged in.
WP Contact Form - A very simple no frills contact form.