Musi-Google

Google has created a timeline of music between 1950 and now. It shows the distribution of genres of music over time (as a share of the whole).

That's cool enough, but then you can click the timeline to explore each genre.

Even cooler, if you type the name of a band or artist, it shows their output / popularity across the entire timeline. If you stay generic (try just using 'jones'), it shows any artist with that name.