Motivated by visualizing overlapping intervals from the This is not Rocket Science blog (by Valentine Svensson) I developed some code in SPSS to accomplish a similar feat. Here is an example plot from the blog: It is related to a graph I attempted to make for visualizing overlap in crime...
Morphet & Symanzik (2010) propose different novel cyclical color ramps by taking ColorBrewer ramps and wrapping them on the circle. All other previous continuous circle ramps I had seen prior were always rainbow scales, and there is plenty discussion about why rainbow color scales are bad...