Try an eggplant lasagna. Not too hard to make, and you would never know there is no meat in it. Lots of recipes
here.
Portabella mushrooms are another great idea either as a topping for all the meat eaters, or as a main course for the vegetarians in the crowd. One I found:
1/4 cup olive oil
2-3 tbsp soya sauce
1 tbsp balsamic vinegar
3-4 portabella mushrooms.
Emulsify with a whisk
Marinate them like 1-2 hours, and BBQ
Again, they taste just like beef and make great low cal burgers. You coud aleays mix the above with fried onions as a steak or roast topping and it would be pretty tasty I'm sure.