OpenDocument is the native format of an increasing number of "Office" tools. It is sufficiently clean and properly designed to be suitable for automatic template-based generation. A project named Documatic, at http://stonecode.svnrepository.com/documatic/trac.cgi/wiki , has started some work on the area. Currently, it supports Text and Spreadsheet OD types.
Therefore, Redmine could probably add OpenDocument to its - already fairly complete - list of view formats.