The Centers for Disease Control lists health concerns for specific countries, including vaccine recommendations, names of cholera and yellow fever-infected countries, and the locations of disease outbreaks. A good site for learning about health risks while traveling abroad.
Lists causes, prevention, and treatment of some specific diseases international travelers might encounter. Also lists advice on first aid kits, insurance, and precautions with food and water.
This site brings daily updated travel health information about dozens of countries. It includes a link to help you locate a travel medicine provider, a section on general health concerns, and profiles of individual countries. An easy to browse resource.
This site has a search function to look for specific health-related information.