Color Selection Charts
Links to standard color charts to help you select a color scheme for your design project:
Hex Code Color Chart
Color Selection Tools (Free):
ColorPix is a useful little color picker that grabs the pixel under your mouse and transforms it into a number of different color formats. Use the built-in magnifier to zoom in on your screen, click on a color value to copy it directly to the clipboard, and even keep ColorPix on top of all other apps and out of the way.
Color Selection Tools (Pay):
I use the color wheel in Adobe Illustrator CS5 & CS5.5 to build out complimentary colors and schemes if I am given 1 or 2 colors to start from and create swatch libraries for my clients.
Another great program is ColorSchemer, which allows for creation of swatches to be used in design software. It is great at kicking out swatches nice & neatly packaged for your favorite design software.