I love using color to help express the style of a wedding and this is such a cool and unique way to do it. It's called Ombre, basically you have colors that look as if they fade into each other which creates a luxurious and unique effect. Here's some amazing Ombre cakes I found.
As seen in El Paso Wedding Blog.
As seen on Project Wedding.
As seen on Maggie Austin Cake.
Cake by a Swiss bakery called Call Me Cupcake.