OpenTBS version 1.4.0 has just been released. It's a simple and practical PHP tool, under LGPL license, to generate Open Document (OpenOffice, LibreOffice) or Open XML documents (Microsoft Office), using templates.
OpenTBS is quite simple to use and to install (a couple of PHP files, one for OpenTBS, another for the TinyButStrong template engine), it needs no EXE, it doesn't use temporary files, only the zLib extension for PHP (very often pre-installed) and OpenTBS can even work without it but it will cost an effort for building templates.
In fact OpenTBS can work with any document established like a zip archive that embeds XML files. This is the case for OpenOffice, and also MS Office since version 2007. You can get the final result as file saved on the server, as an HTTP direct download, or even a binary string.
OpenTBS leans on the TinyButStrong template engine for PHP which is mature and offers many facilities for merging data. OpenTBS can also modify pictures in the merged documents.
TinyButStrong template engine for PHP: