ColorPic

1.     Easily pick any color from the screen
2.     Totally 100% Free!
3.     No popup adverts or spyware, it really is free
4.     Colors shown in hex and decimal
5.     Adjust Hue, Saturation, Value, Red, Green and Blue values
6.     Cyan, Magenta, Yellow and Black percentages shown
7.     Easy to use with any other program
8.     Resizable magnification area
9.     Overlay a grid for quick colorpicker alignment
10.     Use arrow keys to nudge mouse pointer
11.     Save multiple palettes of colors automatically
12.     WebSafe Colors and names displayed
13.     Snap to nearest WebSafe color
14.     Point sample, 3x3 or 5x5 pixel color sampling
15.     Adjust color with four advanced color mixers
16.     Edit colorpicker values after selection easily
17.     Easy to use collapsible sections
18.     Works with Firefox, Internet Explorer, Photoshop and any other application 

Source : http://www.iconico.com