Have everyone write out a special wish/thought/blessing for mom-to-be and/or baby. You could take a picture of mom with each guest and put it together with the comments into a small scrapbook.
Do a "sharing circle" where everyone has a chance to say something positive they learned or experienced in giving birth, or in being a parent.
Have mom/sister/close friend of mom-to-be braid her hair and put flowers in it.
Give mom-to-be a foot bath and massage.
A wonderful quote for just such an occasion is:
"When you have come to the edge of all the light you know and are about to step off into the darkness of the unknown, Faith is knowing that one of two things will happen: There will be something solid to stand on or you will be taught how to fly."
Basically you want to create a very intimate and sacred setting to focus in on mom-to-be and her innate "power" to give birth beautifully
Hope some of those ideas help!