As I follow links, trails and dead-ends my mind opens to the 32768 colors of the 15 bit palette, 4096 colors, colour spaces, reduced pallettes, colour flash, color dialogs and pseudo-random dither.
The technical diversity of the internet is a great challenge. Operating systems and applications' colour spaces don't meet or even talk.

Certain people keep appearing on the jump-lists for COLOR HELP ON THE WEB....

Look for Lynda Weinman's online advice, expanded in her excellent "Coloring Web Graphics" book.
useful !

In San Francisco, Bruce Fraser, Scottish, is harder to find online but his book "Real World Photoshop" is a must for computer-color space understanding, particularly in relationship to offset litho printing.
Keep a lookout and do searches with his name from time to time.

I find that no one site or person has the answers to my questions so I keep looking.
Look towards Canada for Victor Engel, from Advanced Revelation Software for some solid advice and a long list of computer-colour related links. The word from Hawaii. See an animated journey through the 6x6x6 color cube supplied by William I. Johnston, Massascusets.
A useful note from SUN on PC and UNIX systems color.
HMTL 3.2 draft comment from Austin, Texas
Use Dougie's Color Picker in Phoenix
The Joy of Hex, Minnesota has online functionality as does Mediarama's Color Page Builder

The Thalia: Guide: Color page from Katholicke University Computing department, Nijmegen, Holland, is a useful, expanse site.
Visit ColorLab in Spain for a Javascript color facility.
Go to ColorCenter from Idaho for a well thought out colour picker for your colour HTML tags
Web Engineer's Toolbox: 256 Color Picker, is part of Kira's web toolbox, a very professional site. I imagine there is a printed version too.
And finally a sobering image of color as it appears on a black and white monitor.