In 1994, Brown and Williamson, one of the largest tobacco manufacturers in the USA, published a list of 599 additives used to make their cigarettes. The full list can be found here.
Ammonia is formed during distillation and burning, and helps the body to absorb more nicotine, boosting its effect. It is usually found in cleaning products and fertilizers, and toxic in large doses.
Nicotine present in the tobacco, produces a reaction with nicotonic receptors and produces effects on muscles and the brain, providing mild euphoria. Highly addictive.
Honey/ chocolate/vanilla for flavour.
Arsenic gives you bad breath, and is a deadly poison in large doses and prolonged exposure. It is also a carcinogen.
Benzene is absorbed by the lungs and transported to various organs such as the liver, where they are metabolized and converted into highly reactive and toxic compounds. Also a carcinogen.
Cadmium a toxic metal that is used in batteries.