General healthcare  

healthfinder.gov
A Service of the National Health Information Center, U.S. Department of Health & Human Services

mayoclinic.com
Mayo Foundation for Medical Education and Research

familydoctor.org
Health information for the whole family from the American Academy of Family Physicians

health.harvard.edu
Harvard Health Publications

patient.co.uk
A comprehensive one-stop healthcare information primarily designed for UK residents

webmd.com

Healthcare web portal

medscape.com
Collections of medical information resources

Malaysian Medical Resources
Collections of local medical information resources contributed by local specialists

Cardiovascular  

heartcenteronline.com
Online cardiovascular information for the whole family

americanheart.org
American Heart Association official website

chdrisk.uni-muenster.de/ framingham
Framingham risk assessment for calculating your chance of developing coronary heart disease

Oncology  

NHS Cancer Screening Programmes
Cancer screening information by the NHS, United Kingdom