Okay, so I'm a lazy designer/programmer and there are times that I want to make a quick change to a generic template so that it better matches a particular user's site. So what I would typically do is grab a screenshot of a template, and mess with the sliders in Photoshop's Image→Adjustments→Hue/Saturation until it turns into something I like and use the eyedropper to get before and after RGB values. Is this a good, effective or efficient work process? Probably not, and there are probably hundreds of ways to do this better.
So one day, I ran into this mobile stylesheet with a metric plethoraton of RGB values and my regular process wasn't going to work here. After some thinking I figured I could quickly kludge together a program where I could set sliders then paste values into the first box and get the resultant values in the second box.
Finally, making this site gave me a reason to mess around with those fancy shmancy html5 range inputs!
Okay, a half-decade later I figured I'd spend a couple more minutes on this and fix the weird numbers I was getting from my initial formula. Looks like it works a lot better now. Enjoy.