Oregon has legalized or is planning on legalizing psilocin mushrooms for therapy as well as MDMA, I think. There have been some studies as well as a lot of anecdotal info about various psychedelics helping people overcome all sorts of addictions. Ibogaine apparently is very effective for opiate addicts.

Also, there have been at least a few studies on the use of high doses of Cannabis to treat addiction and other emotional issues.