According to the Kuroshitsuji website, there are 6 OVAs included in the DVD releases.

DVD 2: Ciel in Wonderland (Part 1)
This re-imagines the cast of Kuroshitsuji II as characters in Lewis Carroll’s Alice in Wonderland story.

DVD 3: Welcome to the Phantomhive’s
This is meant to be like a simulation game. Elizabeth invites a lady (perhaps the viewer) to join her at a ball held at the Phantomhive mansion.

DVD 5: The Making of Kuroshitsuji II
This is a Hollywood style documentary with behind the scenes interviews with Sebastian, Ciel, Claude and Alois etc.

DVD 6: Ciel in Wonderland (Part 2)
This re-imagines the cast of Kuroshitsuji II as characters in Lewis Carroll’s Alice in Wonderland story.

DVD 8: The Tale of William the Shinigami
William and Grell have to train new shinigami and reminisce about when they were training partners.

DVD 9: The Spider’s Intention
The life in Trancy household and how those work under Alois is caring for him.