Glenn McDonald attempts to graph the musical space in its entirety on a two-dimensional scale. He calls it Every Noise at Once.
This is an ongoing attempt at an algorithmically-generated, readability-adjusted scatter-plot of the musical genre-space, based on data tracked and analyzed for 1491 genres by Spotify. The calibration is fuzzy, but in general down is more organic, up is more mechanical and electric; left is denser and more atmospheric, right is spikier and bouncier.
Click on the genres for music samples, if you are like me and are not sure what rap metalcore or ghettotech sounds like. [Thanks, Namir]