Amy Winehouse. Other great performances: AOL sessions 6th of May 2004, Jools Holland and here, here, here and here for example.
I was very sad to hear of the death of Amy Winehouse at the age of 27. She's truly one of the most talented singers and songwriters of her generation.
I saw her live several times early in her career - a stand-out night for me was the Billie Holiday tribute (Billie & me curated by Neneh Cherry at the Barbican) where she more than held her own. The troubled life unfolding in the tabloids thereafter was sad to see, but I do hope her immense talent is what will be remembered. Rest in peace.
Read more here, here, here, here or here for example.