Here are links to other websites that will be of interest to those studying medieval warfare:
Internet Medieval Sourcebook – hundreds of translated texts
Medievalists.net – hundreds of articles and other resources. See their page on Medieval Warfare for specific resources
Medieval News – news about the Middle Ages, including archaeological discoveries and conference reports
SSCLE: Society for the Study of the Crusades and the Latin East – academic society focusing on the history of the crusades
International Congress on Medieval Studies – annual conference held at the University of Western Michigan which includes sessions run by De Re Militari as well as our business meeting
War of the Sicilian Vespers – detailed website about the late 13th – early-14th century conflict that took place throughout the Mediterranean. Site run by Lawrence V. Mott
International Medieval Congress – annual conference held at the University of Leeds