There are a few decent sources on line dealing with international relations, both from an historical and a contemporary vantage point.
Columbia International Affairs On-line offers access to a wide range of scholarship on security, defense, intelligence and other issues at http://www.ciaonet.org/
Yale University's Avalon Project offers documents in law, history, and diplomacy across several centuries at http://www.yale.edu/lawweb/avalon/avalon.htm
The Asia-Pacific Centre for Security Studies in that region can be found at http://www.apcss.org/
There is an excellent site dealing with war crimes and cases through the Web Genocide Documentation Centre at http://www.ess.uwe.ac.uk/genocide/war_criminals.htm
The Munk Centre for International Studies at the University of Toronto can be accessed through http://webapp.mcis.utoronto.ca/default.aspx
Espionage on the Web
There are many interesting sources on the web dealing with various dimensions of intelligence and espionage. The course outline for HST 540 (Espionage: A 20th Century History) found on this website offers some. If you come across any you think are interesting please let me know.
There is a very good one on the Enigma machine found at http://users.telenet.be/d.rijmenants/en/enigmasim.htm Here you can download a simulator of the famous German coding machine and work on coded messages. The components of the machine are also here to be seen.
For information on the Political Warfare Executive of the SOE check out http://clutch.open.ac.uk/schools/emerson00/pwe_main.html
The International Spy Museum in Washington can be accessed through http://www.spymuseum.org/siteintro.asp
There is a Terrorism Research Centre at http://www.terrorism.com/
A few decent sites dealing with dimensions of intelligence and security issues, as well as academic and practitioner groups are: Jane's Intelligence and Insight at http://jir.janes.com/public/jir/index.shtml Intelligence On-Line at http://www.intelligenceonline.com/ the Canadian Association of Security and Intelligence Studies (CASIS) http://www.casis.ca/http:// and the International Intelligence History Association at http://www.intelligence-history.org/