A few general-purpose colormaps for use with ppmquant -map.  The
naming convention should be fairly obvious:

    245r07g07b05.map
    |   |  |  |
    |   |  |  number of blue shades
    |   |  number of green shades
    |   number of red shades
    total number of colors (r*g*b)

Also, there are some "Netscape-Safe" maps - meaning they use only the color
values 0, 51, 102, 153, 204, 255 (or in hex, 00, 33, 66, 99, cc, ff).
These six color values form a 216-element colormap that is guaranteed
to be rendered correctly by Netscape.