We are big big fans of pot-lucks at Creative Density. In fact we are having one tomorrow and we do them every two to three weeks.
We call them 'We Top a…(salad / taco / burger).
The space provides the base of the meal and then people are responsible for a topping, a fancy bun, side dish, etc. Together we create an amazing buffet of food.
Big bonus: Since people are participating with a food item there is an instant new topic for people to talk about. This makes it easy for new people to get folded into the larger community.