These are some of the games I've played at past parties...
Guess the baby animal.. Bear - Cub, Butterfly - Catterpillar, Fox - Kit...etc Baby Shower Game - Guess The Baby Animal Name - from Partydirectory.com
Guess the baby poop... melt different types of chocolate bars in diapers and people guess what type they are. Gross but funny at the same time...
What baby stuff is in this bag - Buy a lot of little baby things (q-tips, nail clips, bibs, socks, diaper, rattle...etc) Then tell guests how many things are int he bag. they make a list of all the things they think are in there. One with the most corrected guesses wins
Guess how big mommy is... Everyone cuts a length of string that they think fits around the mommy's tummy. Closest size wins
That's all I can remember right now.
I do agree with the ladies, asking to bring the guests to bring diapers is always a big hit with the mom to be!