Flower ceremony for unity piece: we had friends and family bring up a flower representing a diff. value (rose=love, lilies=wisdom, chrysanthemum=faithfulness), then we poured water to tie it all together.
Very neat alternative to the unity candle - You have a flower for the bride and groom, and then each member of the bridal party. They carry the roses down the aisle then add them to the vase. During the ceremony, the bride and groom add their own to the large center vase as well.