Justin O’Beirne has written a nice tutorial to give you an overview of how you can use Google Maps API V3 to create unique map styles. He begins by detailing how your mashups can be improved by removing select map elements, and then He goes on to detail how you can “simplify” other map elements.

After that, He discuss some of the ways in which you can modify the coloring of existing map elements in order to create visually striking map styles. Finally, He discuss some practices to avoid when styling your mashups.

Source: http://www.41latitude.com/post/1268734799/google-styled-maps