Here is a list of color pickers I use when I choose a new color scheme for a project.

COLOURlovers

COLOURlovers is a creative community where people from around the world create and share colors, palettes and patterns.

colourco.de

Colourco.de is an online designer tool, which allows you to easily and intuitively combine colours.

Conva - Learn Colors

Everything you need to know about colors - Find color description, color meaning and thousands of color combinations.

Colorado

Native color picker app for Mac, Windows, Linux.

Grabient

Beautiful and simple UI for generating web gradients.