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.
Another important thing to remember is making sure that you have enough ink in your printer. This includes color and black depending on what kind of game you decide to print out. Allow the print out enough time to dry before picking it up, some games will use a lot of ink and it may still be damp when it's done printing.