I hacked up a quick program last week that lets me plug in my external hard drives, one at a time, and scans them to extract the file names which it writes to a CSV file. (The code is specifically looking for video files and DVD images, but remove that restriction and it could catalogue anything). It works well enough and was just what I needed (finding something on an external drive is tedious when you have more than a handful of them and can't plug them all in at once...), but it's a command-line utility and it would be more friendly to release it as a Windows GUI program.
If anyone feels like wrapping a Windows GUI around this thing, here's the source code. There's a tiny amount of documentation in the top of the C file as comments.
I looked fairly hard and I couldn't find any existing utility that scans drives like this and outputs in a form that a DVD Library Manager could import.
I'm a fairly experienced old-time programmer but I'm sticking with command-line stuff and algorithm development; I really don't have a lot of interest in learning GUI programming myself and from what I've seen of the M$ interface, nowhere near enough free time to learn it all either :-/ However I write *lots* of utilities and would welcome working with people who enjoy M$ programming and find the GUI side of things easy...