I want to put keywords on all my files, not just adobe files and images. It would immensely help my work flow and manage updated and older products. We work with .nlbl file types which do not enjoy the metadata features our psd's and tifs enjoy
That would be up to the file type (and their source applications) to support XMP. XMP is the metadata interchange standard that Adobe applications read and write into their files. Other file types also support XMP, such as JPEG and PDF.
Other applications, especially Camera RAW processors, tend to store metadata in any number of sidecar XML files. In the case of Office XML docs, they have metadata files buried in the package that represents the document, but the documents are really ZIP archives.
Applying tags or keywords to ANY file is precisely why we use Digital Asset Management systems, which often separate the metadata from the binary. Even files that don't support XMP can be classified in a DAM.