NCColors is a tweak that allows you to change the background color of your Notification Center, using RGB sliders. The use of color sliders means you can have basically any color you want. It also updates flawlessly when you edit the sliders, meaning you don't have to respring just to see a color change, which is nice.

I did not make this video, nor am i responsible for the contents of it.

This tweak is available for free from the ModMyi repo.