When it's possible, LIVEditor will provide instant visual feedbacks as you edit your html/css/JavaScript code.
This idea is mainly inspired by Firebug and Bret Victor's mind-blowing Inventing On Principle presentation.
For example, When the code editor's caret is inside a html color value, you hit the [Alt] key and a HSL color picker will appear inplace, and as you hover the mouse above the color space the html preview will lively change accordingly!
Check the screenshots below for better demos:
