The 2003 Cavalier I bought this summer came with one key, and it was missing the rubber part at the key ring end. Today, I had two keys cut from the old worn one that came with the car, but they do have the rubber/plastic piece at the end. My key stops in the right spot in the ignition now, no need to wiggle it around to turn it. I previously thought I needed a new lock cylinder, but these new keys seem to do the trick! Nothing groundbreaking here, but hopefully it helps someone.
You can always take your VIN & registration into a GM dealer and have them cut a brand new key from the original key code..assuming the lock hasn't been changed. I've 'fixed' a couple of otherwise junker J-cars this way... $2 a piece.