Ibogaine is known as a plant that cures heroino addiction basically. You take it, and you trip for like 18-24 hours (I'm going off memory here, so take this with a grain of salt) and afterwards, you don't withdraw from heroin anymore, it totally skips the 5 day withdrawal process. Most people go up to a year with no cravings, before the effect starts to fade off. But by then, you should have changed your life enough that you can keep doing good. That's what I've heard anyways. I've talked to a few people on different forums that took ibogaine to get off opiates and had very positive things to say about it.
edit: Also, various studies have been showing that psychedelics in general are good for battling addiction. However, I've never heard of anything other than ibogaine bypassing withdrawal.