J.K. Rowling may be moving on, but it seems she'll always keep a toe in the Harry Potter universe!
Her most recent short story is a biography of Celestina Warbeck, the "Singing Sorceress" who is mentioned in passing in the original books. J.K. says:
"Celestina Warbeck is one of my favourite 'off-stage' characters in the Harry Potter series, and has been part of the Potter world ever since its inception, making an early appearance in the short-lived 'Daily Prophet' series I produced for members of the equally short-lived fan club run by my British publisher, Bloomsbury. Although we never lay eyes on Celestina during the whole seven volumes of the Potter books, I always imagined her to resemble Shirley Bassey in both looks and style. I stole her first name from a friend with whom I worked, years ago, at Amnesty International's Headquarters in London; 'Celestina' was simply begging to be scooped up and attached to a glamorous witch."
You can read the story on the official Pottermore website, but first take a listen to an actual song snippet from Celestina…AFTER THE JUMP!!!