P.K.
How about a blank book to have people sign and write a loving message in for her and the baby. Also can have a poster board and have them sign it with a picture of the sonagram or couple or mom on it. Could add some pictures of each guest also. If she has a baby book, and you scrapbook, could do something on a scrapbook page to insert in her baby book.
As far as games, been to both with and without games. Most people I've talked with, like it better without games so they can visit and are not rushed. Simple finger foods-chicken salad, mini croissants, fruit and punch are good for and afternoon gathering. Fresh flowers, balloons are pretty. Go with a color theme if you like. Fabric is great to add color. You can pick up remnants pretty inexpensively. You can wrap toole (netting) aroung chandeliers, or banisters for extra punch. You can take mini stuffed animals and tie with skinny satin ribbon to light fixtures and you can easily make a diaper cake. Can find instructions on google.com. best of luck. Cupcakes are great instead of cake. Put on white frosting and color the sugar to match a theme, and dip in colored sugar while frosting is still wet. At my daughters, we gave out cookies from the bakery wrapped in pretty celophane bags and pretty satin ribbon, (which we did). Not too expensive for a couple of dozen. Best of luck.