Add to Your Own Mix with Wikipedia’s List of Colors
I love looking at color groupings, and can spend inordinate amounts of time fingering the paint samples in a building supplies store, or the rows of embroidery floss at a craft or sewing store.
I took a number of classes with Gunnel Hag, a wonderful artist and gifted teacher, who employed color guides in her teaching (such as those by Ikuyoshi Shibukawa). By noting at the percentages listed beside each hue, shade, tint, or tone, you had a very clear guideline as to how to recreate that color.
This Wikipedia list of colors is quite comprehensive and provides the same thing, plus every color is a link to even more information about it.
Extra: Shirley William’s art