Though Colorhexa has this phrase in its title, it is much more then that. Yes, it has a very effective way to present all the relevant information about a color, be it in RGB, CMYK, HSL, HSV and other formats. But what I like the most is having the ability to blend different colors and view different gradients of colors. At that early stage of building a web site, when you play around with different color schemes, this type of site and service are a must.
Yes, there are a lot of color pickers out there. They are a must tool for any web development project. Color Pad is a similar app I reviewed in the past, but Color cop is my new favorite. What I like about Color Cop is the eye dropper feature. In combination with the magnifying glass, it allows you to zoom in on any part of the screen, choose exactly the area you want to investigate and find the color you want, its RGB code and its HTML code. There are other nice features as well, such as various output formats and automatic similar color suggestions. It is free to download and obviously, highly recommended.