Out of the jungle, I would only consider running Smite on Sion for health/gold farming. Not very efficient, but sometimes I just don't have much need for another summoner spell.
@^: Yeah it only counts for spell vamp which is achieved with Vicious Strikes or some items.
I always use Smite with Warwick whether I plan to jungle or not. I usually end up jungling a little bit no matter how the game is going and nothing frustrates me more than when I have the dragon almost dead and someone on the enemy team jumps in at the last minute and steals it so I keep Smite with me to be sure I get the last hit. It also comes in handy to work the other way around and steal those jungle kills from the other team XD
I always use Smite with Warwick whether I plan to jungle or not. I usually end up jungling a little bit no matter how the game is going and nothing frustrates me more than when I have the dragon almost dead and someone on the enemy team jumps in at the last minute and steals it so I keep Smite with me to be sure I get the last hit. It also comes in handy to work the other way around and steal those jungle kills from the other team XD