The only thing I have actually tried, and it worked, was bird netting. But I have heard of:
A rubber snake.
A plastic owl.
Criss crossing fishing line overhead the run.
Whirl-a-gigs.
The CD trick you mentioned.
and of course, using any sort of netting/fencing/what have you to cover it.
The problem with the decoys and CD's and such, so I've been told (mind you this isn't personal experience) is that it only works until they are used to seeing it and have figured out it won't get them.
I've read that plastic netting is too flimsy and it won't work for hawks but it does for me. I even have a picture of a hawk sitting on the fence of my run covered with netting. He never did get in. It will not work, however, for mammal predators like raccoons, opossums, etc. For those you need 1" welded wire or 1/2" hardware cloth.