TopLeaf is a professional DITA and XML publishing system from Turn-Key Systems. TopLeaf combines a powerful rendering engine with a stylesheet development toolkit that allows complex document styles to be set up quickly.
Free plugins are available for integrating TopLeaf into the following environments:
X-ICE is a free, open source toolkit for converting documents into XML. More information, plus a free download, is available here.
Turn-Key can provide everything you need to create and publish XML data, from converting legacy data to generating multi-format output.