I built a color scheme editor for sublime using Angular.js and some HTML5 File APIs. It only works in Google Chrome though, since the HTML5 file apis are not implemented in other browsers yet.
You can drag and drop your color scheme on the page and start tweaking it to your hearts content.
Try it out here: tmtheme-editor.herokuapp.com/
the code is also available on github: github.com/aziz/tmTheme-Editor