Tack another graphic to the growing list of subway map metaphors. Meet the Boss "maps" Google acquisitions and investments, color-coding tracks by industry. The maroon track, for example, represents video, hence YouTube, which also interconnects with advertising and web services.
The design is nothing new (and kind of overdone), but the data are pretty interesting. I've never even heard of most of the acquisitions.
Does anyone know who was the first to use the subway map metaphor?