B.S.
There have been a lot of great responses already!
A game that you could play that's great for everybody is to have a blank "bingo" looking card for all the guests (As many rows as you would like to have nothing specific) Have the guests write down in each block what they think the mommy to be is going to be getting getting for gifts and as she opens the gifts they mark off the square. The first person to get a line wins a prize (have a few runner up prizes as well) here's a link to a sample card!
http://www.babbee.com/baby_bingo/01.html
Hope this helps!