We’ve all got our faves, here are mine!
Adobe Kuler
Kuler is awesome. You can create your own color schemes from a color or an uploaded image, but the best part is the massive amount of color combos created by Kuler users. You can use Kuler directly through Illustrator too, so no need to deal with downloading and adding the swatch set manually. Kuler also has an app where you can pull a color scheme from anything.
Color Peek
Color Peek is way more than just a color picker. It was created by Tyler Sticka to solve the issue of having to type hex values into Illustrator (or whatever you software you use) over and over to simply show a color scheme to someone. Color Peek let’s you easily assemble swatch sets in the browser. There is also a Chrome extension that grabs the color schemes from any site and let’s you easily add them to your collection. It’s really excellent, I need to remember to use this more!
Piknik
A fun one! Perfect for grabbing a quick HEX while you are mocking something up or just playing around. I love using this one in demos.
Any others you like? Comment away.