Actually the Chrome DevTools can save your changes back to disk! It's not well known, and its fairly new so I don't blame ya.
Here's how it works: (1) make changes to styles as you do (2) you can click through to the Sources pane and live-edit styles there, just like a text editor. (3) Right click and save to disk. choose where to save the file (4) Make some more changes (5) Just hit ctrl-s (or cmd-s) to immediately save back to disk in the same location.
I just made a screencast to show this in action: http://www.youtube.com/watch?v=Qy5obNItQiQ