As a wedding planner, I do have an emergency kit that I bring to all the weddings I coordinate. There are many things in there that might just come in handy on the most important day for my clients. Emergency kits aren't only for the brides, it is for everyone, even the groom, bridal party and the parents. If you have a wedding planner, great, make sure she or he will take care of it for you.
But if you don't have a wedding planner, why not put together a list of things you might need for your emergency kit, email the list to your bridesmaids and split the items among everybody and have each person bring a few things on the list. On the day of your wedding, prepare a bag for all the emergency items, dump all the items in the bag and give it to someone in your bridal party or someone who will always be close by on that day. You never know who might need a little hairpray or tissue during that day!
The Knot has put together a list of things that you might want to include in your emergency kit so that your day can go off without a hitch.