There are tons of color pickers out there. The main difference in Photoshop-Like Javascript Color Picker is that it has all 6 picking options (H,S,V,R,G,B) not just Hue. To create the color mixing, the larger map is made of two layers and the vertical slider has four layers (two are used for H, S, or B; four layers for R, G, or B). Some others pickers use this method for a hue map, but don’t include the other maps (S,V,R,G,B).The JavaScript is made up of some color methods, a slider control, a handler for input, and the ColorPicker object to put it all together.

Requirements: IE5.5, IE6, IE7, FF2, Opera 9, Safari 2
Demo: http://johndyer.name/lab/colorpicker/
License: License Free