I got my bridesmaids little bumble bee charms from James Avery.  With each, I sent a note about how important their friendship was to me, how they had shaped my life, how I couldn't imagine standing up at the altar without them, and asked them to “bee” my bridesmaid/moh/etc. 

They all said that they loved the little charms and have loved wearing them.  I didn't get them chains because I knew they all had one and I didn't want them to feel obligated to wear them… Just an idea!