DOWNLOAD: Yosemite GUI Mode Toggle Workflow
With either a shortcut or hotkey you can toggle between normal and dark mode in Yosemite AND thanks to the recent Alfred update, the Alfred Theme!
To make the workflow universal this switches between the Yosemite themes included with Alfred 2.
To change to your own "Normal" and "Dark" Alfred themes, be sure to modify the script lines accordingly:
For Normal Mode change the name:
tell application "Alfr