I'v used this freeware for around 2-3 years now. It's a great little tool if you use photoshop or create websites.

Ctrl + Alt + C is the basic hotkey you will need.

Pixie is an easy-to-use, fast and tiny utility designed especially to fit the needs of Webmasters and Designers. Its 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. You can then use these values to reproduce the selected colour in your favorite programs. Pixie will also show the current x y position of your mouse pointer. Its the only tool you'll need for working with colours.

With greater power Pixie is still slim enough and still live in 8Kb only. Deserved software does not have to be huge.

Check it out or download here: [link]