There are 100s of lists with the top 10 or 15 or 20 WordPress plugins on the Internet and here’s mine. These are plugins I use on pretty much every WordPress installation. They all work with WordPress 3. You may not need all of them, but you never know.
1. Akismet
The essential spam filter that accompanies every WordPress installation. http://wordpress.org/extend/plugins/akismet/
2. Automatic WordPress Backup
You can’t have too much money and you can’t back up too much. As the name implies this plugin automatically backs up WordPress files and database tables to Amazon S3 (Amazon Simple Storage Service). That’s industrial-strength reliability at minimal cost or even free. http://wordpress.org/extend/plugins/automatic-wordpress-backup/
3. Disable Parent Menu Link
This simple, settings-free plugin only does one thing and it does it well. It disables the link of a parent page in the WordPress menu. http://wordpress.org/extend/plugins/disable-parent-menu-link/
4. EmbedIt
Ever have the WordPress visual editor eat your code or script? This plugin lets you enter the code as a Custom Field then place just the field name in your post or page. Read more here or http://www.matteoionescu.com/wordpress/embed-html/
5. Google Analyticator
Google Analyticator adds the code for Google Analytics and has a few options for viewing Google Analytics’ results in your admin or as a widget. http://wordpress.org/extend/plugins/google-analyticator/
6. Login LockDown
Lock down your login. Login LockDown limits the number of login attempts from a given IP range within a certain time period. It helps prevent hacking where a computer tries every possible password until it succeeds. It also keeps track of IPs that were locked out. http://wordpress.org/extend/plugins/login-lockdown/
7. Query Posts
Query Posts is for widgets. It provides almost every imaginable way to show posts and pages in the sidebar. Combine it with Widget Logic below for almost limitless control. http://wordpress.org/extend/plugins/query-posts/
8. TinyMCE Advanced
Named after its partner, TinyMCE, the WYSIWYG edit built into WordPress, TinyMCE Advanced adds loads of additional editing capabilities like Search and Replace and Tables. http://wordpress.org/extend/plugins/tinymce-advanced/
9. Widget Logic
Widget Logic adds a little text field to every widget where you can tell the widget to appear only on the page you want it to. It uses WordPress’ conditional tags so it may not be for everyone, but it sure is useful if you have a little php experience. http://wordpress.org/extend/plugins/widget-logic/
10. WordPress SEO
Dutch WordPress plugin master, Joost de Valk, also know as Yoast, offers a powerful plugin that does almost everything SEO. http://wordpress.org/extend/plugins/wordpress-seo/