Color Cop - Converts RGB decimal values to RGB Hexadecimal Triplets. Includes a built in color picker, preview, and an eyedropper to choose colors anywhere on the screen. Windows 95/98/NT/2000. - http://www.prall.net/tools/colorcop/
Html color picker - Picks colors and shows the HEX color equivalent. [Requires .NET Framework] - http://www.good.za.net/product.asp?Id=1
La Boite a Couleurs - Free Windows graphic tool to pick, modify and convert colors (models: RGB, HLS, HSV, CMY, CMYK). PDF help file is available. - http://pourpre.com/colorbox/indexen.php
Kokya - Windows software to manipulate, create and save color palettes. Convert any color to its closest Web safe equivalent. - http://www.adsystemsit.com/software/kokya
ColorCoder - Aids in composing colors trough RGB, HLS, CMY, CMYK and YCbCr color models. Allows you to copy and paste hexadecimal representations, save colors to palette, and capture colors from your screen. - http://www.downi.com/colorcoder/
Colourificator - Color picker for Windows. - http://septor.screaming.net/