American Cancer Society
It's pretty common knowledge that smoking is linked to lung cancer, but it's also associated with bladder, cervix, kidney, stomach and uterine cancers, so the American Cancer Society (ACS) works hard to help smokers quit. Their online "Guide to Quitting Smoking" includes information on the health, economic and social benefits of quitting, along with resources to help smokers deal with the mental and physical addictions.
The ACS Web site is very realistic about the success rates for people who quit smoking: Those who quit completely on their own have just a 4 to 7 percent chance of staying smoke-free. They recommend professional help, like behavioral therapy, to increase those odds, and they also encourage smokers to look into medications, which increase the odds of quitting successfully to 25 to 33 percent.
Like QuitNet, the ACS resources include information on fighting the weight gain that often comes with quitting smoking, and suggests physical activity and getting involved in spiritual practices to help cope with stress without cigarettes.