A game I played with my kids who are now grown and i do it with my grands when needed is the Little Red Schoolhouse. The rules are everyone has to be silent and the first one to talk loses! It works great in the car!! You can have prizes if you want I never did it was just for fun. It helps get the noise level down for awhile anyway!!.
I also used to sing with the kids. It is a great way to bond and it gets their attention off whatever the noise was about. I also used this in the car but my grands love to sing with me now. We do what ever kid songs and other Christian ditties I learned as a child like Jesus loves me or we do things like 5 little monkeys jumping on the bed for the little ones. It is fun and gets their attention when you want them to calm down.
A tip I learned when I worked in daycare was to sit down and begin to clap your hands. Vary your clapping over your head - under your leg or change the rythm and kids will stop and join in most of the time. You can also snap your fingers or do a Simon Says sort of thing. Can you pat your tummy and rub your head? It works to get their attention.
One more thing we did was when the noise got too much we would shut off the light and make everyone sit down somewhere. It makes a point that the noise is too high.