Running wild with the recycling idea ...
The field is covered with hundreds of recyclable objects (say, Crackerjacks, Haagen-Dazs cups and Diet Coke cans), scattered all over. The robots have to pick up as many as possible and
deposit them into appropriate containers (plastic, cardboard, and metal). Two of each trash type bin, one for red team, one for blue. Scores are easy to calculate: +2 points per object in the right bin, -1 per object in the wrong bin. (Double the points during the 15 seconds of autonomous mode.)
Strategies could include:
- Dumping objects in the wrong bin of the other alliance (to cost them points)

- Blocking the bins of the other alliance
- Strong alliance partners would have the ability to accurately discern one particular type of object; "dream teams" would consist of three 'bots, one of each type.

- The objects could be as simple as different colored balls (nerf, poof, kick, etc.), or as complex as spheres, cubes, and cones (each shape different colors, have to be sorted by shape?
) - Objects could start above the player stations (a la FIRST Frenzy, 2004), to encourage randomness
Okay, that's 2 minutes of thought.