Napa and Sonoma have their wine tours, and travelers flock to Scotland to sample the fine single malt whiskies. But in Jamaica, farmers are offering a different kind of trip for a different type of connoisseur. Call them ganja tours: smoky, mystical — and technically illegal — journeys to some of the island's hidden cannabis plantations, where pot tourists can sample such strains as "purple kush" and "pineapple skunk."