These types of lists are ten-a-penny, so I don’t expect you to see this list as definitive. It is however part of a larger conversation, and I welcome your input on which of these plugins you use all the time, or whether there are some I have missed.
These plugins are plugins that I will install on at least 75% of installations. Some of them however go on every installation without a second thought.
All In One SEO Pack
This plugin has long been the go-to plugin for adding SEO functionality to your installation. If you have any interest in search engines taking you seriously, you need to install this plugin and take the time to write meta descriptions and decent post titles for every post.
Monitors your WordPress installation for exploits and spam injections and lets you know if it finds anything.
Contact Form 7
Every blog without fail should have a contact page, and this is the perfect plugin for creating a secure contact form. Of course, it’s highly extensible and can be used for much more than just contacting the author – you can collect any information you like in a secure form.
Disqus Comment System
WordPress’ default commenting system is really good, but what it lacks is any sort of social aspect. Disqus is really good because people can share their comments, sign in using Facebook or Twitter and “like” a post. Disqus also looks for mentions across social networks.
WordPress’ RSS feed is pretty good, but really you need to then it into a FeedBurner feed and make the most of it, like permitting subscription by email, adding ads and getting detailed statistics about your feed.
Google Analytics for WordPress
Google Analytics is the most informative and easy-to-read statistics program out there and is provided free of charge by Google. Use this plugin to activate it on your site to find where your visitors come from, what your most popular content is and where visitors are leaving your site.
Google XML Sitemaps
Sitemaps are an easy and essential way of letting search engines know what is on your site and how important you deem each page to be. This plugin builds the sitemap for you dynamically and even lets the big search engines know when it changes.
A simple plugin that lets RSS Cloud-ready services immediately know when you publish any new content, so there’s no delay in your information getting out to your audience.
Gives you a rundown of essential security measures that you should be taking, highlighting them as red or green, so you can easily see where you need to take action. Perfect for initial setup or a security review.
Social media is a growing force in online traffic and you want to be sure you’re giving your readers ample opportunity to share your story. This little sharebar floats unobtrusively at the side offering little buttons to share to Twitter, Facebook, Buzz, Digg and email.
Theme Authenticity Checker
This plugin scans your theme files daily for suspicious code which may have been injected. If it finds anything, it’ll send you an email and ask you to have a closer look.
An extremely handy and customisable toolbar that sits at the bottom of your screen, providing links for sharing content, searching for content, subscribing and community features.
WordPress Database Backup
Backing up your database is an absolute must. I wrote another article showing how to use this plugin to automate your database backups so that if the unthinkable happens, you’re not stuck up shit creek without a paddle.
Seamless and powerful integration between your blog and your Twitter. Even better when paired with WPTouch. If you’re not on Twitter, you’re missing out on a huge traffic source.
WP Super Cache
This acts as both a performance enhancer and a safety net. It markedly reduces the load of requests on your server, making it more responsive and speedier (something that is purported to play a role in search engine ranking now) as well as avoiding a server crash if your post gets a lot of attention in a short space of time (such as a popular post on Digg).
As the world gets more and more mobile, it’s ever more important to offer a mobile site that’s audited for smaller screens. WPTouch does so seamlessly and works beautifully out of the box as well as providing a whole host of configuration options. Very possibly my favourite plugin.
Yet Another Related Posts Plugin
When readers get to the bottom of your post, you need to provide them with other reading options, so they stay on your site rather than heading elsewhere. This plugin looks for similar posts on your blog and suggests these in a list in order of how relative they are to the current post.
Well, that’s my two cents for what it’s worth. Is there anything missing from the list? What plugins do you rely heavily upon?