What plugins should I use on my Wordpress blog to improve it?

There are hundreds of WordPress plugins availible, and opinions vary on which are the "best" to use, or the "most important." The "top five" seem to be: 1) A good anti-comment-spam plugin (or editing your .htaccess to blog at the source) 2) A "related posts" plugin (shows posts that are theoretically related (by keyword) to the current post) 3) A "top posts" or "latest posts" plugin. 4) The RunPHP plugin (http://www.nosq.com/2004/10/runphp-wordp... ) (allowing you to execute PHP code in your posts and pages). 5) The Subscribe to Comments plugin (http://txfx.net/search/subscribe%20to%20... ), allow people to receive e-mail notification when comments are replied to. The Wordpress Codex contains many plugins, and links to outside plugin lists. Additionally a search on yahoo for "wordpress plugin" will merit a lot of results. Ultimately, it's your blog, feel free to use what you prefer.