Will, I know that OCLC's ContentDM supports JPEG2000 (see http://www.oclc.org/contentdm/about/displaying/default.htm). A directory of institutions using ContentDM is available at http://www.contentdm.com/customers/index.html I assume some of them are using the JPEG2000 extension.
Good Luck! Tom Scheinfeldt Assistant Director, Center for History & New Media Research Assistant Professor, Department of History & Art History George Mason University http://chnm.gmu.edu/ http://www.foundhistory.org/
