The standard face pull performed with a rope or handles is great for back development and posture. Here's how to make it even better.
Reach your hands through a band, anchoring the band along the outside of the wrists. Turn your palms down. Now use the standard "elbows up and out" form, pulling to your nose or forehead. Squeeze at the top.
The band will add side-to-side resistance, forcing you to fight hard to spread the band apart.