The classic use for unwanted or scratched CDs is as coasters. We've offered up lots of alternatives in the past. Here's a useful addition to that list: stopping Indian mynas and other birds from savaging plants in your garden.
Picture by Top Left Design
I've spotted mobiles made from CDs in gardens in the past, but never realised that the discs served a functional purpose. However, the Twig gardening column from the Australian pointed out a while back (I just found my notes) that the light reflected from CDs makes them "effective deterrents" for scaring away Indian mynas and other pests. It's certainly a low-cost, non-toxic alternative if you want to keep birds away from treasured foliage.