I know what not to do. A few Christmas ago, someone had the bright idea to get people to get to know each other and mix it up a bit. Everyone got a fabric swatch as they entered which matched a table fabric swatch. The idea was to get to know other people. Wrong. It was not fun not to sit with my friends and talk to them about their Christmas. Don't get me wrong. The idea would have been fine at another "table" meeting. Just not Christmas.
A few fun things that have been mentioned is have a cookie contest, a postcard swap, an ornament exchange.