First let's get the semantics out of the way: They haven't called them head shops since the Seventies. The preferred moniker these days is smoke shop, though if all you're after is a good stogie, turn around and head for a cigar store. However, if your smoking urges -- nudge, nudge, wink, wink -- require some preparation, Sativa is the place. Sure you could pick up an oversize bong at any of several garish spots along Washington Avenue on South Beach. And if you're just looking to stay abreast of the latest market trends, the current issue of High Times is available at plenty of newsstands. But at Sativa the friendly staff also has your postsmoking needs in mind: A wide variety of self-detoxification kits is on display here, perfect for those occasions when your employer takes a sudden interest in your urine.