Debcha sez, "Dorian Lynskey presents a London Underground map, transmogrified to represent music and musical influences. Each major line is a style of music (for example the Circle Line is pop, and the Docklands Light Railroad is classical), each station is labeled with the name of an artist. Junctions are artists working in two or more genres, and the branch lines are used to represent musical divergence (eg rap diverges into old-school and New York rap). I love the Tube map, and music, and mashing them together makes my head explode with joy."
(Thanks, Debcha!)
Update: Here's Laura Cantrell's C&W/NYC subway map version of this — thanks, Jeff!