The Panakranta, also known as Kyriotissa, Queen of Heaven, She Who Reigns in Majesty
While you're here, do you know anything about Solrunn Nes and her book, The Mystical Language of Icons? I'm thinking of getting it.
http://www.christusrex.org/www2/cantgreg/cantus/regina_caeli.mp3
This is sung after High Mass, during the Easter season of the liturgical year.