Here are some little guys I did over the course of an hour or so. The starting point for the Pac Man was two pennies for the top and the bottom of the mouth. Then you cut a ball of clay in half and add above and below the pennies. Finish with a layer of yellow clay and red for the inside of the mouth.
The ghosties are simple. The only elaborate creation is the bottom. The way I did it was to push some of the clay up and some down in an alternating pattern.