Public Health

PubMed (same data, different skin as Medline / Ovid)
This is the premier source for medical research; You can often find medical intervention studies here. Created by the US National Library of Medicine, it contains references to authoritative information on medicine, nursing, dentistry, veterinary medicine, the healthcare system, pre-clinical sciences, and much more. Note: PubMed is a public portal into the same underlying data which is in the Medline/Ovid databases. These other databases, which are meant for medical professionals, have more advanced options but are less user friendly.

CINAHL
The world's most comprehensive full text database for nursing & allied health journals, providing full text for more than 610 journals indexed in CINAHL. Of those, 317 are not found with full text in any version of Academic Search, Health Source, or Nursing & Allied Health Collection.

Web of Science
Broad database that is most useful for the 'harder' end of the social sciences (e.g. psychology), health sciences, and natural sciences. This is a good place to look for intervention studies. It is also useful for evaluating the relative importance of a particular article to the field. 

Alt HealthWatch
This database provides full-text access to over 200 publications on complementary, alternative, holistic, and integrated approaches to healthcare and wellness.

Family Health Database (Proquest)
This database is distinctive for its coverage of popular journal articles and magazines aimed at consumers. Good for looking at authoritative health advice aimed at a non-professional, public audience. Subject range "from sports injuries to women's health, from food and nutrition to midwifery, from eye care to dentistry." 

NICE - National Institute for Health and Care Excellence

NICE clinical guidelines are recommendations on the appropriate treatment and care of people with specific diseases and conditions within the NHS in England and Wales. They are based on the best available evidence and aim to improve the quality of healthcare by changing the process of healthcare and improving people's chances of getting as well as possible. NICE clinical guidelines:

• provide recommendations for the treatment and care of people by health professionals

• are used to develop standards to assess the clinical practice of individual health professionals

• are used in the education and training of health professionals

• help patients to make informed decisions

• improve communication between patient and health professional

NICE produces guidance in three areas of health:

• public health - guidance on the promotion of good health and the prevention of ill health for those working in the NHS, local authorities and the wider public and voluntary sector
• health technologies - guidance on the use of new and existing medicines, treatments and procedures within the NHS
• clinical practice - guidance on the appropriate treatment and care of people with specific diseases and conditions within the NHS

National Guideline Clearinghouse

Contains - evidence-based clinical practice guidelines from many organizations.

NGC is an initiative of the Agency for Healthcare Research and Quality (AHRQ), U.S. Department of Health and Human Services.

The NGC mission is to provide physicians, nurses, and other health professionals, health care providers, health plans, integrated delivery systems, purchasers and others an accessible mechanism for obtaining objective, detailed information on clinical practice guidelines and to further their dissemination, implementation and use.

See also, More Databases for Evidence Based Medicine