This graph uses two hues, blue and pink, to show its data. Blue
represents boys' names, and pink represents girls' names. Within
those colors, the color value represents the popularity of those
names in 2003. A third color, dark gray, shows the frame around
the data -- the grid lines, the numbers, and the title -- and a
dark blue highlights the selected name ("Dale").
This color combination is very effective, both cognitively and
aesthetically. The hues and values mean something with respect
to the data, and the coding is very easy to follow -- you hardly
even need the legend once you've looked at it once. Aesthetically,
the whole thing has a layered richness that isn't garish, as
rainbow hues would have been. And in American culture, people
understand light blues and pinks as "baby" colors, so the
emotional and cultural connection is there too.