One of the difficulties in trying to quit smoking is that smokers become physically dependant on nicotine. Smoking affects the parts of the brain that relate to reward and pleasure. It increases the amount of the neurotransmitter, dopamine, and the nature of nicotine is that it creates a cycle of positive reinforcement within your brain that makes you want more.
Scientists have found that when you withdraw from chronic nicotine use, it results in changes in these neural pleasure pathways. And the effect on the brain is similar to what someone addicted to cocaine, opiates and other drugs experiences. Hence, depression and anxiety are common.
Fortunately, some resourceful modern herbalists began applying traditional knowledge to a modern problem. In Ayurvedic medicine, common garden variety oats (but not oat straw), is used to treat opium withdrawal. The herbalist Anand, using a tincture (an alcoholic extract of the herb), applied this same reasoning to nicotine withdrawal, with significant results.
In a group of 26 heavy smokers, he gave an oat tincture, and in another group of 26, he gave a placebo. The group who took the oat tincture smoked less cigarettes, and this effect remained for two months after they stopped treatment. The herbalist Weiss theorizes that it is the sedative effect of oats. Oats contain as active constituents the indole alkaloid, gramine, and the alkaloids avenine and trigonelline. Oats are described in herbal medicine texts as helping create a feeling of well-being whilst simultaneously acting as a tonic to the nervous system. But unlike narcotics, these are mild, non-habit forming effects.
My herbal teacher, Ses Salmond, suggested the following formula for those trying to stop smoking. In a 50ml bottle, mix the following herbal tinctures:

• 15ml green oats
  
• 10ml white horehound
  
• 10ml mullein
  
• 5ml golden seal
  
• 10ml peppermint

Take 6 drops on the tongue whenever the craving to have a cigarette is felt.
Acupuncture is also an excellent support option. HerbMed offers the following herbal option, to be used on appropriate acupuncture points. Mix oil of cloves, oil of wintergreen, an extract of evodia fruit, an extract of sichuan lovage rhizome, and msg, and apply to specific acupuncture points. Unfortunately, they don't say which acupuncture points, but this may be determined by what each person presents with.
Resources: 1. www.herbmed.org/herbs/herb36.htm

2. Class notes by Ses Salmond

3. C Fisher & G Painter, Materia Medica Of Western Herbs For The Southern Hemisphere

4. R Weiss, Herbal Medicine (Beaconsfield Arcanum, 1988)

5. www.drugabuse.gov/Infofacts/Tobacco.html