you can make sun catchers for your window with them. http://makezine.com/projects/peel-paint-cd-sun-catchers/
My friend took photos of her children/grandchildren, and attached them to the old CD's and then trimmed them with fancy bric a brac and used them to trim a "Special" tree for Christmas, which stands in her front foyer each holiday season..
Try looking under the craft section of home talk to see what others have created and maybe an idea will spark.
Pintrest may have some ideas.
if you are a gardener this idea is a great way to keep birds and some animals out of your garden. punch a hole in the edge of the cd and put a piece of string through the hole. it does not have to be long, just enough that the cd can twist and move in the wind. tie them from poles or run a rope from one end of the garden to the other. the flashing just freaks the birds and animals out and they will stay away.
Make a room divider. You can Google CD room dividers and lots of images come up. Lots of great ideas.
I saw a photo of them used as a backsplash which is something I dream of doing.