However, there is a simple way to adjust some of the colours and settings of these essential elements without having to write clever scripts (or copy them from the Internet ;)): install Gnome Colour Chooser from the Ubuntu Software Centre.
- From the Applications menu, select the Ubuntu Software Centre
- Type Gnome Colour Chooser into the search box
- Install the application
Once installed, you'll find the application shortcut in the System → Preferences Menu and just click the icon to open the program.
One of the real benefits is being able to change the properties of the font (colour, size, and style), allowing you to use dark backgrounds without loosing sight of your menus, but there is a host of options to play with and you can have hours of fun designing (should that be, redesigning?) your theme.