Here is a page where you can click on the colour you want, and the code will be automatically added to your clipboard. You can then paste it into your image editor's colour selector. Works well.
A good website for graphic designers. It reminders me of the color picker in Adobe illustrator and photoshop
I don't have Photoshop, so I'm not sure how that works. You can pick any colour in PhotoImpact and get the code for it, but this works externally, picking a colour then pasting the code into your colour picker. I like the simple click and copy function.
This sounds a bit like Color Cop, though the latter may have more functionality. See http://colorcop.net/features/