we had a baby blessing for dd. everyone who attended did part of a henna design on my belly and i asked them to send their love and positive thoughts to the baby as they did it.
i also got some embroidery thread and tied a piece around everyone's wrist. we asked them not to take it off until they received word that the baby had arrived. the thread was to serve as a reminder of the baby's impending arrival, and anytime they touched or saw the thread, they could think good thoughts abou the birth or send love to the baby. i felt like it was important that i was the one tying the thread onto the guests, as the thread retained mine and the baby's energy. what is really cool about that was that mine and dh's parents' strings fell off the day i was in labor, and we hadn't called to tell them about my being in labor until after dd was born, but all of them mentioned the string falling off that day when we did finally call.
the other thing i know is done sometimes but we didn't do is to ask each person to bring a bead that is signifigant to them, and the beads would be strung into a necklace for the mother to wear while birthing her baby. as the beads were strung up at the baby blessing, each person explains to the mother what the signifigance of their bead is. it can be a bead they wore while birthing, it could be a bead that they just picked up at the store b/c it made them think of the mom, you know, whatever they think is special about it.