Tagit is a command line tool for tagging files. It could be used as a quick'n dirty way of organising a media library.
npm install -g tagit
cd ~/Music // Or anywhere where you have your files
tagit init // Initialize internal database
tagit update // Recursively scan current directory and add all files to the index
tagit autotag // Tag all files in the index extracting tags from filenames
tagit tagged rock // List all files tagged with 'rock'
tagit tagged rock heavy // List all files tagged with 'rock' and 'heavy'
tagit random // Pick a random file
tagit random pop // Pick a random file tagged with 'pop'
tagit tag my_song.mp3 favourite // Tag my_song.mp3 with tag 'favourite'