You never know when a client may want you to take one set of documents and get them ready for cross-media publishing on every conceivable platform. XML Spy fits in this category. From Icon Information Systems, XML Spy is an inexpensive shareware program that lets you edit XML, HTML, XSL, RDF, 3DML, and DTD files. It gives you three views of your document, including a grid view, source view, and a browser view using Internet Explorer. The program is available through XML Spy or from a variety of software download sites, including TuCows.
Icon also offers multi-user and site licensing arrangements.
XML Pro from Vervet Logic is another relatively inexpensive, but comprehensive, XML editing tool. It has an Element Wizard and an Attribute Wizard to help speed up the creation of elements and attributes. You can insert database content into your XML document as HTML tables or as XML code. Both companies have long histories of developing systems to help publish authoring systems for technical documentation, so both have parlayed that experience into creating XML content-creation tools.