I've seen bbs, buckshot, airsoft bbs, golfballs, and get this, anti-freeze, used to balance tires. There are even sand filled balancing rings available that go between the wheel and brake. I'm using off-road dynabeads which are too big to go through, or get stuck in the valve stem. At one time I had a wheel with half the rim covered in lead trying to balance a 37" swamper. The dynabeads took care of that problem.
Tire shaving is pretty interesting. It would really help in some cases, like really big tires which aren't very round from the factory. Most shops don't have the equipment though.