Customize your GNOME desktop!
 * change most important colors (e.g. background, window decoration, tooltips)
 * change sizes of widgets (e.g. of buttons, scrollbars or the main padding)
 * allow use of light-colored wallpapers without getting icons unreadable
 * adjust the size of start menues / panel menues / or large-toolbars
 * colorize desktop icons and activate their new hover effects
   (requires GNOME 2.18+)
 * configure your gtk engines and let your current theme be drawn by whatever
   gtk engine you want
   (requires GNOME 2.18+ or engines that support engine schema definitions
    respectively)
 * many more

http://www.punk-ass-bitch.org/gnome-color-chooser/