The more involved games come at a cost but it is usually nominal, a few dollars at the most and you have a unique game to keep the guests entertained. The best board games to be found are usually question and answer games, where the guests partner up and try to answer questions about the couple or each other for points or spaces on the printed out board. Many games are able to be customized so that you can enter specific questions about guests or the expectant parents to print out.
Meanwhile to tickle the right side of the brain, there are numerous line drawings of each of the popular Cars characters that are available from various internet sites. A printer and scanner if available can translate these into hours and hours of creative silence. Copies can be duplicated in as many times as the child wishes to enjoy the pursuit, perhaps using and changing colors on the same picture as he pleases. These same pages can later on, with some help from mom or dad, be cut out and turned into an improvised jigsaw puzzle. And while on the subject, the same cut outs can be used as wall decors for the child's room, or as colorful covers for their notebooks and folders.