Yes, Virginia, there is a magenta - Ars Technica
http://arstechnica.com/science/news/2009/02/yes-virgina-there-is-a-magenta.ars

Magenta isn't a single color on the visible light spectrum: but it exists anyway. With diagrams.

Yes, Virginia, there is a magenta - Ars Technica

Beautiful multi-band images of the Milky Way

for video giving instructions, see http://blog.chromoscope.net/2009/12/what-is-the-chromoscope/

שבי להחלב באורכי גל שונים

Electromagnetic spectrum with a lot of histories!!

the electromagnetic spectrum, a radial image with a lot of information