The following websites have more information about Ultimate Sacrifice, President Kennedy, and the history of US-Cuba relations.

JFK Lancer
JFK Lancer has as wide variety of JFK assassination information on their website, as well as a Forum for discussions about various aspects of the case. They also publish an e-newsletter that features the latest news about JFK-related topics. At their annual JFK Conference in Dallas, slated for November 17-19, 2006, historians and authors present their latest research. This year's Conference will feature a presentation by Lamar Waldron of files shown for the first time in the trade paperback of Ultimate Sacrifice, as well as new documents from the National Archives that provide further proof for the book: http://jfklancer.com/

Spartacus Educational
Spartacus is part of the world's largest educational website. One portion includes detailed biographies and photos of major and minor figures who have been linked to JFK and his assassination, including many of the people named in Ultimate Sacrifice: http://www.spartacus.schoolnet.co.uk/JFKindex.htm

They also have a large online Forum for discussions of various topics related to the JFK assassination, including several threads on Ultimate Sacrifice:
http://educationforum.ipbhost.com/index.php?s=48573a0db773746d8bd43322047548f2&showforum=126

The Mary Ferrell Foundation
Named for the late Mary Ferrell, one of the leading JFK researches of all time, their site has the largest collection of declassified JFK assassination documents that can be viewed online. They also feature breaking news about the case, video interviews with various authors and experts, and much more: http://www.maryferrell.org/wiki/index.php/Main_Page

They feature a "Document Walkthrough" of files cited in the original edition of Ultimate Sacrifice, as well as exclusive video interview clips of Lamar Waldron, talking about the book. Soon, new files will be added from the updated trade paperback:
http://www.maryferrell.org/wiki/index.php/Document_Walkthrough_-_Ultimate_Sacrifice

National Archives and Records Administration
This page highlights the JFK records collection at the National Archives II, in College Park, Maryland. Much of the collection can be searched online, and documents can be ordered by mail or viewed at Archives II. Several hundred pages in the special "ARC" collection can actually viewed online, including some of the US military files about the "Plan for a Coup in Cuba." http://www.archives.gov/research/jfk/

US State Department
The following links are part of the "Foreign Relations of the United States" series. They contain declassified files that relate to covert US actions against Cuba, including several key JFK Administration meetings from 1963. Note that in their version of item #374, "Almeida" is misspelled "Alveida." http://www.state.gov/www/about_state/history/frusXI/index.html

JFK Assassination Records Review Board
The Final Report of the Review Board, authorized by Congress and appointed by President Clinton, is available on this website, hosted by the Federation of American Scientists: http://www.fas.org/sgp/advisory/arrb98/index.html
Of particular note is Chapter 8, Part 3, which talks about the January 1995 Secret Service destruction of files covering the period of the Chicago and Tampa attempts. The Secret Service also admitted destroying files about the Fair Play for Cuba Committee and threats to JFK in Dallas: http://www.fas.org/sgp/advisory/arrb98/part11.htm

National Security Archive
The National Security Archive is an independent research institute and library located at George Washington University, which collects and publishes declassified documents obtained through the Freedom of Information Act. They have several document collections related to US-Cuba relations, and the actions of several veterans of JFK's coup plan/AMWORLD in Guatemala and Chile: http://www.gwu.edu/~nsarchiv/

Cuban Information Archives
Founded by Gordon Winslow, the former Archivist for Miami-Dade County, this site features a wide variety of files and photographs related to the JFK assassination and US-Cuba relations, with a special focus on Cuban exiles: http://www.cuban-exile.com/index.shtml

There are many more excellent web sites about the JFK assassination and US-Cuba relations, and more links will be added soon.