I'm a little crazy about meal time, but I feel like meal time is really the core of the family, so it's important that it is pleasant and respectful. We have certain rules, like no yelling, saying please and thank you, cleaning your mess when you're done, staying at the table until we are all finished, etc.
Right now I think the biggest rule we have is to share nicely... I'm hoping I'll get through to them one day.