Is there an application for creating an text inventory of media files and/or applications
I would say the best way to do this would be some sort of script that searches your drive on a scheduled basis, and dumps the results into a text file for you.

Something like:

sudo find / -name "*.avi" -o -name "*.mp4" -o -name "*.m4v" -o -name "*.mp3" &gt; ~/Dropbox/results.txt


The -o switch is the find equivalent of logical OR, so the above is searching the whole of your computer for any files (or directories) that have the extensions .avi, .mp4, .m4v, or .mp3