Although the Obama administration released nine previously undisclosed memos from the Bush era Office of Legal Counsel, a number of memos remain secret, and the existence of others was revealed by the memos that were disclosed.
The ACLU has a complete list of the memos that have and have not been release. There are many still missing, but it's notable that a number of them have to do with the treatment of prisoners under the Geneva Conventions and the obligations of the United States regarding international treaties that relate to detainee treatment. There are also a number of memos regarding interrogation procedures used by the CIA and foreign intelligence activities that remain undisclosed. While the content of the memos released earlier this week was quite dramatic and included arguments from John Yoo that the President could ignore Constitutional protections when fighting terrorism, I get the sense we're still on the upper half of the iceberg. The full list is here.
-- A. Serwer