Another couple of gems from Ken DeHart and the Top Tennis Tips From Around the World DVD and I will stop R&D'ing his material -
You may recall an earlier blog post called Battle Cones (if not, click on the link). This one is similar in that the object is to be the first player to hit the opponent's cone. However, this one is played up close, inside the service boxes and only uses one cone per player.
Players warm up cross court inside the service box. Each has a cone inside their own service box. In Ken's example, the cones were more or less in the middle of the box. Warm-up commences. First player to hit opponent's cone wins.
I would add a ball to the top of each cone for added excitement and eliminating any doubt about whether the cone is tagged. Switch to other half of court and repeat. As a progression, restrict shot selection to forehands, backhands, or all slice.