Photographers have used black Plexiglas for a long time to shoot everything from products to flowers to portraits. I just took this portrait of my neighbor's daughter, Grayci, using only one studio light - a White Lightning strobe and small softbox.
The dark reflection from the Plexy adds an elegant and intriguing quality to anything you shoot with it.
This was taken with a Canon 5D Mark II and a 24-105mm lens. The aperture was f/18, and I hand-held the shot.