WordPress

WordPress is a "state-of-the-art semantic personal publishing platform with a focus on aesthetics, web standards, and usability." WordPress is easy to customize and use--quite a powerful blogging script. Some WordPress features include:

• Instant publishing with no rebuilding
• Full web standards compliance
  Integrated blogrolling features
• Password-protected posts
• Custom fields
• Dead simple upgrades and installation
• Easy to customize
• Multiple authors
• Multiple categories
• Sub-categories
• Post to future
• Post by email
• Uses PHP and MySQL

For more about WordPress, visit the WordPress.org web site.