html2db.xsl converts an XHTML source document into a Docbook output document. It provides features for customizing the generation of the output, so that the output can be tuned by annotating the source, rather than hand-editing the output. This makes it useful in a processing pipeline where the source documents are maintained in HTML, although it can be used as a one-time conversion tool too.
AFT (Almost Free Text) is a document preparation system. It is mostly free form, meaning that there is little intrusive markup; AFT source documents look a lot like plain old ASCII text. It has a few rules for structuring your document, more to do with formatting your text than embedding lots of commands, and it produces all types of output (HTML, XHTML, LaTeX, roll-your-own XML, etc.). All that needs to be done is to edit a rule file. You can even customize your own rule files for specialized output.
HaXml is a suite of libraries and tools for manipulating XML documents in Haskell. It includes a parser, a pretty-printer, a validator, a combinator library for transforming documents, and converters for changing a Haskell datatype into an XML DTD, and for changing an XML DTD into a set of Haskell datatypes. There are also tools for a query language based on XQL.
Elvis is a clone of vi/ex, the standard UNIX editor. Elvis supports nearly all of the vi/ex commands, in both visual mode and ex mode. Elvis adds support for multiple files, multiple windows, a variety of display modes including "hex" and "html", on-line help, WYSIWYG printing, and other miscellaneous extensions.