There sure is something that I love about pictures that have incorporated an umbrella into them. Umbrellas are not only used to block out the rain, but they are also used for a fun bridal party shot, or a romantic husband/wife shot. Sometimes, the umbrella is also used to hide the bride as she walks a far path to get to the aisle. I have coordinated a few outdoor weddings where the bride provided umbrellas to all of her guests to keep out of the sun and into the shade. 
Here a few websites that I have found that offer some cute umbrellas to use in your wedding:
The above pictures are from Aaron Snow, Candi Coffman, and Christian Sangree with Prints Charming Photography from Oklahoma (and Jasmine Star and Evoke Photography).
What have you decided to have down your aisle?