Compass Box: Using the "Navigation" and "DriveBase" sub-systems, create a "TurnToCompassHeading" command. Then, create a CommandGroup that can move in a small square (first moving North, then East, then South, then West).
Simple Square: Using the "Navigation" and "DriveBase" sub-systems, create a "TurnLeft" command that will turn the robot 90 degrees counter-clockwise. Then, create a CommandGroup that can move in a small square (move, turn, move, turn, etc.).
Dancing Robot: Define a simple sequence of moves for Grace to perform, and have her do them. (This can't just be moving forward and backward, but it doesn't have to be this, either).
More challenging
K-turn: Create a command group (including any new commands needed) to make the robot perform a "3-point turn". (Hint: you'll need to be able to move both forward and backward into various turns.)
Better Compass Box: Can you implement the "Compass Box" challenge from above, but also make the robot always wind up facing in the same direction that it started? (This is somewhat harder than it may sound.)