I had a client request a blue background for a professional portrait. Rather than purchase another roll of blue paper, I decided to try a different approach. The set up was a neutral gray paper background.
Three lights. A background light with a blue gel covering an Einstein 640 light/Pocketwizard PowerMC2, a main light (a second Einstein 640 shot through an umbrella) and a hair light (SB800/Pocketwizard FlexTT5) shot through a soft box. These were all controlled with Pocketwizard MiniTT1/AC3 on the camera (D800). This is a very easy set up and by simply changing the gel, I can get a different color.
The final result: a clean professional portrait. Obviously, one can apply many different photoshop tricks to create some fun images.