ColorPix

This is a handy little app for web and graphic designers. The user can mouse-over any pixel on the screen and it will display the associated color in RGB, HEX, HSB, and CMYK color modes. You can grab a color, "lock" it on the ColorPix view finder, and copy the color index to the clipboard. This utility can save you a lot of time - especially when your client wants to use "the color on such-and-such website".

There are similar applications out there, but this is the one I ended up liking best. (I only test drove 2 of them)

Website: ColorPix by Color Schemer