One really simple hack I have seen a couple of people do for softening flash is putting some white paper tape over the flash on their camera.
One of the chaps who works the nightclub photography scene in Galway used to do that, and based on the quality of his output, I reckon it worked pretty alright as a "quick fix".
Yeah, once it makes the light source bigger, essentially, it's softening the light. I've used a large white bounce card to soften my fill flash in a pickle, as you can see here: