Over at his Core Dump blog, Keith Soltys introduced me to the Ditaval File Generation Utility by Suite Solutions. The free utility (which is for Windows only) scans the files in a ditamap and lists values for the product, platform, audience, and otherprops attributes. You can check the list to be sure the values are right and then generate a ditaval file.
I haven’t used this tool yet myself, but I can think back to a project where it would have been very helpful in tracking down just a few incorrect attribute values lurking in hundreds of DITA topic files. At the time, I used TextPad to search on all the files within directories, but I could only search on one attribute name (or flaky value) at a time. If this utility works as advertised, it would eliminate that problem.