1) WordPress
This free blog software is b2/cafelog's official successor. It has a great interface and useful features like 'private' posting (password-protected), file uploads, and more. You need PHP version 4.1 or greater, MySQL version 3.23.23 or greater, and The Apache mod_rewrite module (optional, for the nice URI functions) on your server.
2) Blogger.com
This is one of the most popular free blog hosts. Users can create a personal or a group blog for free - either by using their hosted service (BlogSpot) or one's own web host.
3) Movable Type
This is a popular blog software among bloggers who like to manipulate web designs, formats, and functions. However, you need to have some programming skills (or pay for an installation service) and your own web host. While there is a free blog version, some bloggers might find the licensing agreement with this too limiting. For more flexibility, there are several licensing fee options for both personal and commercial users.
4) Greymatter
It is the 'original opensource weblogging and journal software' on the web (Read: Free blog platform). Installation to a server that supports Perl 5 software is required. It has several features like comments, 'karma' voting, templates, search, and bookmarklet.
5) Live Journal
This popular free blog host is preferred by many individuals who enjoy a community-based blogging system. It is web-based and the sign-up process is quick and easy. There's also a premium version.
6) Multiply
This is where blogging meets social networking. It also supports photo blogging and video/audio uploads. There are three membership levels: Free, Gold, and Platinum.
7) Xanga
This free blog platform is web-based. There is also a 'premium' (paid) version. It is growing in popularity, especially because of its community. Just sign-up and you will get a free blog going soon enough.
8) 20Six UK
This is a UK-based free blog host that has some nifty features including image hosting, statistics, categories, RSS/XML feed, voting, and comments functions. One special feature it has that many blog hosts don't offer is the support for mobile blogging (posting to your blog using MMS and/or email). They have recently introduced paid versions of this blog system.
9) MindSay
This free blog system offers features and plugins including templates, friends' list, favorite links, music playlists, recent visitors list, comments, and ratings.