We use them to store robot parts; great for packing up a project at the end of the day so that all the pieces are together when you come back the next work day.
We have used them as a "trunk" on our robot cart to carry batteries, tools, and the driver station.
We also secured a couple to some 1 x 12"s, added a couple of squares of RR tape and included them as a target in our
off-season game.