A few things about my last couple of posts. The first is that if you can get the list of your libraries from somewhere else (Data View page made in SharePoint Designer, Powershell, etc) then you can pull the GUIDS from any list. I tried it on non-Project Site libraries and it works fine.
The second is slightly more exciting – as long as your list isn’t too long, you could take your positive results (the ones which do have documents on them) and run a web query on the table (it appears to be table 5) to return the list of documents and all their info. I tried the code I found on the Excel Forums, and it works great!