I like the clothes pin game. It's easy and fun. At my shower, we did a "dirty diaper" game. Someone put different kinds of baby food in a couple of diapers and guests had to guess what flavor of baby food was in each diaper. The one who gets the most correct wins. It's kind of gross, but funny. We also did a game where guests had to guess how big around my belly was. Each guest cut off a piece of yarn, and the whoever's yarn came closest to fitting around my belly won.
As for decorations, balloons are quick and easy; also a couple of those huge bows in pink or blue. I went to a baby shower last weekend where they had framed ultrasound pics on each table. It was really cute!
I scrapbook (occasionally anyway
and anytime I have a party I glue the invitation in the center of a sheet of scrapbook paper and have all the guests sign around it. That takes care of half of my layout and it's nice to look back on later to see who was there. Plus imo, it makes more sense than a guestbook that just ends up in a box somewhere. You might could even have guests create scrapbook pages at the shower and she could fill it in with pics later. I would have loved that.
For food, I would go pretty simple. Maybe you could order a cake and have some of your family help with the rest.