I changed my brakes and rotors last week. Any suggestions on what to do with the old rotors? I purchased the new ones via Atlantic British. It seems like a waste to just toss 100 pounds of metal in the trash. 
On a side note, if you are changing your brake pad sensors, I'd recommend doing the rear one first. As has been mentioned in numerous other posts, the connector for the front sensor is hidden behind the wheel well plastic and is extremely difficult to see. Doing the rear one first gives you a good sense of how the connector works, thus allowing you to blindly change the front sensor with just your hands.

On a side note, if you are changing your brake pad sensors, I'd recommend doing the rear one first. As has been mentioned in numerous other posts, the connector for the front sensor is hidden behind the wheel well plastic and is extremely difficult to see. Doing the rear one first gives you a good sense of how the connector works, thus allowing you to blindly change the front sensor with just your hands.