CSSColorEditor lets you ... edit CSS colors (visually)
Replacing the color scheme for a site using CSS can be an annoying task. The same color may be used for several elements across the file, and you need to search and replace for it. Color is represented by hex codes, which is not very visual. This is not a problem heavyweight web developers have -- they're usually set up with advanced text editors which feature built-in color pickers.
Users just starting out with CSS, however, often have to struggle with the color codes and with visualizing how the scheme fits together. CSSColorEditor (another great find from MakeUseOf) aims to help with this exact issue. It's a simple one-purpose tool, which lets you load a local CSS file, change its colors using a visual color picker, and then spews that same file out with different colors. The color swatches are too small for my liking, but they still give you a clue as to what the scheme would end up looking (I'm color-blind, so don't judge me in the comments!)
Another minor UI niggle is that the picker dialog itself does not have an "OK" button. Where you would expect that button to be, there's actually a link leading you to another site. That's kind of weird, too.