Nice one, travelled back in time a bit. One thing that was unexpected for me is when you hover on the circles in the Known Uses section of a color, I expeceted that the given OS will be shown as a tooltip (maybe also clickable) and I don't need to click on the "View all X palettes" link. But lovely idea, thanks for sharing.
Ah, I can see! The dots mark years (not OSs) since multiple OSs might use the same color in the same release year. However, you're totally right: the tooltip is dearly missing since it would make just that obvious - and also a default action when clicking a dot.