15 Gallon Barrel Structure

I have a very large supply of 15 gallon plastic barrels. They're 2 feet tall and about 14 inches in diameter. What can I do with them? I've thought about drilling a bunch of 1/2 inch holes all over and then putting some weight in the bottom. All of the holes in the barrel would allow it to provide safety to minnows, etc. Maybe drop them in 3-5 feet of water to simulate a stump? Or would I be better off to make a large version of CanePole's coffee can structure?

Would they work for shallow spring time structure? Or should I sink them deep?

Thoughts?

Here's a picture of the barrels.
http://i538.photobucket.com/albums/f...g/P1030512.jpg