A new patent filing shows a new technology that turns a flexible OLED display into a speaker membrane. This is only possible with a flexible display as the membrane needs to vibrate. This is a cool invention that may turn any flexible display into a large-sized speaker. I'm not sure if this won't harm the display quality, but this is still a novel idea.
In past years we've seen several OLED related patents from Apple, mostly dealing with flexible OLEDs for mobile devices. In June 2012 for example, Apple filed for a new patent that describes a wraparound flexible transparent display that enables new form factors. In March 2013 Apple filed a patent that describes an option to include multiple transparent displays, overlaid on top of one another.