One of the most important sites you will want to be familiar with is the CDC. This is a government site that provides extensive, searchable information and statistics related to prevention, incidence, and immunization guidelines related to communicable diseases. It includes full text copies of the MMWR (Morbidity and Mortality Weekly Report.)
It also gives information on diseases and conditions, with links to many related sites on those topics. A great starting point for case studies and patient education reports.
