This awesome color picker was originally written by Daniel Rind, then improved/updated by Chris Johnson.
Last version is for Max 8/9 though, and I don’t have Visual Studio 2005 to recompile it with (nor the necessary chops). Maybe someone here could help?
Source is here:
http://www.idigitalhouse.com/Tech/dh_tech.html
I also talked with Chris about porting this to Photoshop since the color picker there sucks so bad. Unfortunately the adobe SDK is hard to come by, but maybe someone here would love to tackle this? I know Adobe has integrated Kuhler across the CS line, but that’s not really as helpful for texture painters as a picker palette would be.