This recipe is amazing - and while it's got sour cream, I'm pretty sure you could at least use a light variety:
(If you can get access to the original one from America's Test Kitchen, all the better - but I think the above link is pretty close. It is so good...)
Otherwise, like nelie suggested, skewer some bell pepper, onion, mushroom, maybe zucchini.
You can grill most any vegetable! Asparagus is amazing. Turnips are surprisingly awesome, too!