XMLmind XML Editor allows to edit large, complex, modular, XML documents. It makes it easy mastering XML vocabularies such as DocBook or DITA. (More info.)

As you can see it in the screen shot below, XMLmind XML Editor is not a tool for programmers. Its users are generally technical writers.

oXygen is a cross-platform XML Editor. Besides the top-of-the-line XML source editing support, it features a CSS driven WYSIWYG XML editing mode allowing the content authors to visually edit DITA documents. oXygen features include out-of-the-box integration with the DITA Open Toolkit and can be easily customized to match your DITA editing and publishing needs.

DITA Storm™ Developer (www.inmediusdita.com) is a full-featured DITA editing tool that enables authors to easily create DITA-compliant content in WYSIWYG mode regardless of their DITA or XML knowledge.  The editing environment is 100% browser-based, requiring no timely or costly client installations or updates, and is completely customizable for a superior DITA user experience.  Non-technical authors create structured content in a familiar environment while ensuring that the entire DITA documentation lifecycle is supported through easy integration into an exiting CMS.

The XyEnterprise Contenta DITA Solution enables authors, editors, reviewers, translators and managers to automate workflow, re-use and share content, manage review cycles and translation, and publish to multiple channels.  Seamless integration with the DITA Open Toolkit provides single source publishing to print, PDF, Help, Web and CD-ROM.  Along with XyEnterprise’s suite of XML solutions, Contenta DITA was developed on an open architecture that ensures maximum scalability and investment preservation.

Astoria On-Demand is a fully-web hosted and accessible xml content management solution for content publishing to the DITA standard.  Astoria manages and automates the creation, review, assembly and publishing of technical content, such as technical product information, where content is complex, is re-used, shared and/or re-purposed across multiple langugages and delivery channels.