Since Apple decided to mess with the DigitalColor Meter application in Lion, I've been on the hunt for a new colour picker.
Gradient looks like it could be a good replacement. It gives you a nice menu bar based colour picker, as well as outputting all the CSS code you need to throw in a stylesheet for a nice looking gradient. It's in beta right now and you can sign up at the website for a preview download.
I'd still like the ability to grab a single colour code out and I can't seem to find a way to do that without getting the whole gradient CSS code. But Gradient.app makes a nice option for web work.