Using cooking vessels on gas grill

My experiments with throwing a pizza stone onto a grill worked really well this year so I'm wondering if a gas grill can be used with other cooking vessels. I love donuts and french fries but hate the mess, can I heat up a cast iron pot on a grill and make them outside? How about a flat cast-iron grill? Can I throw that on my Weber and heat it up?

I'm guessing the biggest issue will be temp control, but wondering if people have tried this and found it not to be too difficult.

-Jay

I use my cast iron skillet on the grill all the time to make blackened catfish.
We used a cast alum. griddle over a turkey fryer gas burner
to sear a couple of pounds of Foie Gras
way too smoky to do inside.

Don't have a gas grill, but used my cast iron skillet to do potatoes on my charcoal grill, which gets pretty f'n hot. I would not use an enameled pan, but cast iron dutch ovens should do OK.

Alton Brown uses a wok over his lit charcoal chimney starter, something I've been meaning to try.

I've used an enameled roasting pan on a gas grill to roast a chicken. The type of pan I'm talking about is the old-fashioned black-white-speckled pan. I put the chicken on a metal rack inside the pan. I light up one burner and keep the roasting pan to the side, and the grill lid closed. Just like oven roasting without heating up the kitchen.