There a basically hundreds of great plugins for WordPress depending on what you are looking for when it comes down to customizing your site. These plugins will change depending on if you are creating a niche site, personal blog, portfolio, photo blog, etc.
Here you find all plugins I recommend on a fresh install.
With Akismet you’ll be almost entirely free from spam. I can’t recall any time when Akismet failed to delete an spam comment. Unfortunately it will sometimes block legitimate comments.
Broken Link Checker
After a few entries there will be sites closing down, entries removed and other things influencing your links. Since Google isn’t a fan of broken links I’m using Broken Link Checker to receive errors every time links are broken.
Cforms is a powerful and feature rich form plugin for WordPress, offering convenient deployment of multiple Ajax driven contact forms throughout your blog or even on the same page.
Google XML Sitemaps
To be sure that Google will find and index all of your entries you should create a sitemap, which can easily be done with Google XML Sitemaps.
No Self Pings
Avoid getting trackbacks from yourself with No Self Pings. It doesn’t look very good to have a bunch of trackbacks for an post leading back to you.
Subscribe To Comments
Make it possible for your visitors to Subscribe To Comments and get new comments directly to their inbox.
WP Greet Box
Greet your visitors and convince them to subscribe for your posts with this plugin named WP Greet Box. Show different messages depending on if your visitors came from Google, Facebook, Twitter, etc.
WP Super Cache
Reduce loading time with WP Super Cache. This plugin is not only for big sites with several thousands of visitors each day, but also great to reduce loading time on small niche sites.
Yet Another Related Posts Plugin
Show related posts with YARPP and allow your visitor to find more interesting content on your site.
This sums up to 9 different plugins I think everyone should use. How many and which plugins do you use?