Cubehelix color scheme

Cubehelix is a color scheme that retains contrast as it is desaturated (top), as opposed to a more typical rainbow scheme (bottom). It’s great for look-up-tables (LUTs).

Dave Green’s web site has multiple implementations of the color scheme, including code for R and MATLAB.

More…
Colorblind-proof color schemes
Daltonization

By the way, the If We Assume blog has many great posts on the graphical presentation of data.