How do you get everyone to help out at a family dinner??

What a fantastic idea! I love it! But to enlist the help of my family, I am not nearly as creative, I just call out thier names, tell them a job to do and they usally do it. I have found that a cheerful disposition in the kitchen invites help. I know I get more help when I am not grumpy. When I get in a bad mood in the kitchen the family runs for the hills!