Spectroscope 1.1 is a colorpicker. After selecting your color from the screen it will display RGB values both decimal and in Hex (all Windows versions).

There's also a 2.0 version available now! It lacks the Mac look the 1.x releases had, but it has loads of powerful options added. Like clipboard functions, palette switches, advanced customization of a color and it remembers up to 5 colors. If you're developing webpages, you should give it a try (free, all Windows versions)!