Color Pickers

Colorpicker a free and open source cross platform desktop software for determining the color on the screen

ColorPicker App – screen color picker application for Linux Desktop

sK1 Color Picker – advanced color picker application with magnify glass and palette management functionality

Gpick is an free and open source advanced color picker and palette editing tool for Linux

Pick – a software for picking colors on the screen in Linux

Gcolor3 – free open source software for color choosing (on-screen color detection) and color selection in Linux