Ideas for Christmas Eve Family Church Service | eHow
The article is actually about making kids who don't want to come to the separate children's worship service want to attend it, but I think it could be easily adapted to make kids feel welcome in worship overall when you don't have a separate service.
What a great tradition to start.... Have family put money in mason jar throughout year. At Christmas time, choose someone to bless (anonymously). On Christmas eve, deliver by Ring and Run. Must read the book "The Christmas Jar" it explains how it all started. I love this story!