How about some Wallace & Gromit-esque contraptions? I'm thinking rollaway nest boxes that triggers cupfuls of grain to be released every time somebody lays an egg, or perhaps a windmill that fills up the water drinker? What about a see-saw that they could run up and down?
If it's just for fun, why not make up a website for your enterprise, with live streaming webcams of the hens at work? You could do some in-depth career histories on your "meet the team" page: "Henrietta has two years experience in the egg laying business, having graduated from pullet school in 2009. She is particularly partial to cabbage leaves, and will jump higher for a worm than any other chicken in Britain. Her hobbies are kung-fu, and listening to classical music."
If that was all just a step too far (it's 06:30, and I'm waiting for my porridge to cook!), one of our neighbours has a run door with a hole cut out in it the shape of a chicken, and that looks pretty smart. Perhaps a hen shaped weather vane on one end of the coop?