Smoking
Also called: Cigar smoking, Cigarette smoking, Pipe smoking, Tobacco smoking
There's no way around it. Smoking is bad for your health. Smoking harms nearly every organ of the body. Cigarette smoking causes 87 percent of lung cancer deaths. It is also responsible for many other cancers and health problems. These include lung disease, heart and blood vessel disease, stroke and cataracts. Women who smoke have a greater chance of certain pregnancy problems or having a baby die from sudden infant death syndrome (SIDS). Your smoke is also bad for other people - they breathe in your smoke secondhand and can get many of the same problems as smokers do.
Quitting smoking can reduce your risk of these problems. The earlier you quit, the greater the health benefit.
Overviews
Smoking & Tobacco Use (Centers for Disease Control and Prevention)
Smoking Ups Men's Rheumatoid Arthritis Risk Most (12/24/2009, Reuters Health)
Menthol Cigarettes More Addictive to U.S. Minorities (12/10/2009, HealthDay)
States Slash Funding for Tobacco Prevention Programs (12/09/2009, HealthDay)
Health Headlines: New Smoking Danger, Another Cell Phone Warning, Holiday Safety Tips 
(12/05/2009, HealthDay)
Smoking and Seizures (12/01/2009, HealthDay)
U.S. Adult Smoking Rates Remain Stalled (11/12/2009, Centers for Disease Control and Prevention)
Bidis and Kreteks (Centers for Disease Control and Prevention)
Cigarettes and Other Tobacco Products 
(National Institute on Drug Abuse)
Also available in Spanish
Cigars (American Lung Association)
Hookah Smoking: Is It Safer Than Smoking Cigarettes? (Mayo Foundation for Medical Education and Research)
Truth about "Light" Cigarettes: Questions and Answers (National Cancer Institute)