Well, there are PDF libraries in PHP that you can use to create a PDF; and there's a class called "phprtf" which will create Rich Text Format documents which Word will read.
There's also the PEAR extension for OpenDocument. Not sure if Word will read it (it should) but it's better than nothing.
HERE is a good presentation by Rasmus Lerdorf (spelling?) about PDF creation and editing in PHP. Hope it helps.