WordPress

WordPress is a state-of-the-art publishing platform with a focus on aesthetics, web standards, and usability. WordPress started as just a blogging systems, but has evolved to be used as full content management system.

Its feature includes Cross-blog communication tools (both the Trackback and Pingback standards), Comments, Spam protection, User management, Password Protected Posts, XML-RPC interface, Workflow, Intelligent text formatting, Multiple authors, Bookmarklets, etc.