Android: LifeDropper is a tiny app that uses your phone's camera to snap a picture and present information about the dominant colour in the centre of the frame. It's meant to be used just like the "eyedropper" tool that's in nearly every image-editing app in existence, except instead of being used on a screen, it's for real life.
It provides RGB, CMYK and the hexadecimal value for whatever colour is snapped, and those snaps can be saved in a "tag gallery" to be viewed later.
The app is currently in open beta and completely free (ad-supported). It does require that you be able to install non-market apps (sometimes called sideloading) since it's not on the Android Market yet. You can enable that function by checking the box marked "Unknown Sources" in your phone's Applications Settings.