I can\'t find any packages to do this. I know PHP has a ton of libraries for PDFs (like http://www.fpdf.org/) but anything for Node?
Looks like there's a few for pdf, but I didn't find any for Word.
CPU bound processing like that isn't really Node's strong point anyway (i.e. you get no additional benefits using node to do it over any other language). A pragmatic approach would be to find a good tool and utilise it from Node.
I have heard good things around the office about docsplit http://documentcloud.github.com/docsplit/
While it's not Node, you could easily invoke it from Node with http://nodejs.org/docs/latest/api/all.html#child_process.exec