HTML color codes, color names, and color chart with all hexadecimal, RGB, HSL, color ranges, and swatches.
RGB Color Picker and Pen
What would a book containing every color in the world look like? Behold Tauba Auerbach’s RGB Color Atlas
Mathematical Formulas and Tables - RapidTables.com. Includes symbols and what they stand for.
Free RGB Color Picker - freergbcolorpciker.com
HTML Color Code creators are great. When I'm working with a client on a new website, we often sit down together an try out different colors. So much easier than me deciding myself.
Colorpickle is an easy and customizable #jQuery color picker plugin which enables the user to pick HEX/HSL/RGB colors from a pretty nice palette interface with draggable sliders.
This small web app helps you to copy the colors from Flat UI. It's kind of responsive, so you can use it with a tiny browser like a widget. http://flatuicolors.com/
Super want this. RGB Color Picker pen...any color you see, scan it and then write with it!!