These color charts contain an approximation (the numbers are exact; the colors as close as technology can get them) of a color palette that will not dither when viewed on the web. The center 6 columns contain the 216 non-dithering colors; the outer two columns (pure shades of red, green, blue and black) are for reference.

I also have my 'Color Checker', a javascript utility that will let you experiment with different color combinations, a lesson on the hexadecimal number system, a set of important color definitions, and, last but definitely not least, links to
VisiBone, undoubtedly the Web's most complete source of color and web information. (in my opinion anyway...)