Hate the In-The-Cave look of flash photography? The answer lies in the airline Barf Bag. "Yes, that’s right… Those cute lil’ white plastic bags that the airlines keep tucked away in the back of every seat are absolutely perfect for diffusing the harsh beam of a direct flash. Just one barf bag (a/k/a: “flight discomfort bag”) stuck onto the top of a flash head will mellow out the light dramatically — especially for more “close in” sort of work — and the way that light gets sprayed in all directions can really help in raising the overall brightness of a room and background."
Simply cut away any extra pieces, attachments, cardboard, etc, and apply it to your flash with a bit of low-stick tape, and flash away.
Tip from Matthew G. Monroe from The Global Photographer