I think this cracked article has some really great insight on addiction.
5 Life Lessons You Only Learn Through Quitting Smoking | Cracked.com
I can really understand a lot of the habitual and self delusion aspects of this article despite not smoking.
EDIT*
Oh yeah and Im addicted to playing with my scalp. I do it whenever I get stressed. Its gotten better though I remember I used to like plucking out my hairs. Not sure what else. Maybe the computer sometimes but I can usually keep it in check when I need to or when im busy.