Alcohol, drugs, nicotine, caffeine ... You can get addicted to a lot of stuff, but how about "tanorexic's" addiction to tanning, addiction to nasal spray and even an addiction to reading?
Clinical psychologist Jeff Gardere of Healthguru lists some of the world's most unusual addictions: Link [embedded video]
"Laboratory rewards can establish compulsive self-administration habits of seeking and ingesting that qualify as addiction (1).Rats and monkeys have been shown to work in a compulsive manner to achieve intravenous injections of stimulants, and when access to the drugs is not limited, they will self-administer the drugs to the point of severe weight loss and death.[2] This demonstrates that the habit of self-administration for intracranial brain stimulation or drug injections becomes compulsive almost immediately. BSR is hypothesized to be so effective in establishing compulsive habits because it bypasses the synaptic barriers in the sensory pathways to directly activate the reward pathway. The lack of delay in the reinforcement of a behavior motivated by BSR increases its effectiveness because even a delay of 1 second between the lever-press and the reward delivery can reduce its effectiveness .[2] BSR offers insights into the neuroadaptations involved in reinforcement and addiction."
http://en.wikipedia.org/wiki/Brain_stimulation_reward
http://en.wikipedia.org/wiki/Nucleus_accumbens
http://www.scholarpedia.org/article/Reward