Oooh! You could add drainage holes in the bottom and use them as planters! And you can paint them in fun colors :)
Put plants in them put lights in them make a terrarium in them
I used to take any large containers that I had in the spring and put small holes around them then sink them in the ground around and between the plants in the garden. I would then put my fertilizer water in the containers and put the lids on them to keep the bugs and animals out of them. They worked well for a slow release watering system without having to purchase soaker hoses and all. Note that I only put fertilized water in the containers as recommended on the fertilizer label, the rest of the time I used just water. I checked the containers once a week or more often in really dry hot weather to see if they needed to be filled again.