Pixie is only 62k and free
You can get it at
http://www.nattyware.com/pixie.html
Pixie is a colour picker that includes a mouse tracker. Run it, simply point to a colour and it will tell you the hex, RGB, HTML, CMYK and HSV values of that colour. It has Hotkeys for copy and paste, colour mixer and magnifier.
It is a wicked little tool that I use all the time