Unless you've been living under a rock, you're probably aware of Proposition 19, the ballot measure Californians will vote on next week that would make marijuana legal for all adults and deliver an unprecedented blow to our nation's wasteful, ineffective, and destructive prohibition on a plant less harmful than alcohol. But you may not have heard that voters in a handful of other states will have opportunities to advance saner marijuana laws on Election Day, as well. Two states, Arizona and South…