The newly announced Bluebird theme for XFCE and Gnome has a nice clean look. Using this metacity theme and the Zuki Blues theme, I went all Blue for May. Included are Chromium and Firefox personas also in blue. Below are my results and a link where to get the themes...
The Zuki Blues theme can be found here:
The Bluebird metacity theme can be found here:
Chrome Bluebird theme: