In previous versions of Mac OS X,
CandyBar allowed you to customize the icons and the dock. However, it is not yet compatible with Mountain Lion. Hopefully it'll be updated soon.
I use the Obsidian menu bar modification from
Max Themes, which turns your menu bar black. They also have a 2D etched dock mod available now.
I attached a screen shot of my current desktop so you can see the menu bar in action. It blends in well with the black bezel of the display:
http://cl.ly/IPTS