This is the basis of the massive overarching ID3 extension that I wish I could create, called "Attribute Tags". A large set of tags for you to populate by hand, upload to the Attribute Tag server, then allow others to download and have automatically appended to their files using a tagger program.

On my drive home, I would have loved to hear "uptempo" "major key" "funky" "female vocals". Or, rather, press the "similar to" button while listing to Ani Difranco - Hat Shaped Hat. Would have given me all the happy female vocal tracks from genres like Folk, Pop, Ska, Dance (really House), etc.

I should just shut my mouth, quit my job, and dedicate my life to creating this, because that's the only way it's getting done (without hiring a software creating team to create a product that would be free).