I have also used many of the ideas on this forum,
Another thing that I did that was great was that I used receiving blankets instead of ribbon to wrap around each of the cakes tiers (Folding the blankets diagonally and then attaching it at the other end with a safety pin).
Wrapping each tier with a large rubber band is also necessary. I also bought a cheap baby toy from Winners or Walmart and put it at the top of the cake for the added effect.
Within the cake you can also intermittently place things like baby lotion, shampoo, diaper rash creap, onesies, shoes, mittens, socks ... just about anything that is baby-ish.
I made one for my sisters baby shower and it was truly a hit! People were ranting and raving about it for weeks!!
Good luck! Have fun with it!