These are the few things that come to my mind when speaking of cds.

There are companies out there that produce promotional cds. These discs have very odd shapes. The cds are balanced but can be stars, ice cream cones, cars, rabbits, just to name a few. They also print custom designs. Even though these cd's are a little pricey, you can always record a cd, print an image on it and cut it to the desired shape. As long as you preserve the center of gravity and have an intact readable circle within the shape, you'll be okay.

Compact discs are "burned" to store data and read using lasers. They can reflect light and IR. They fly extremely well and shatter to lots of pieces if broken correctly.

You scratch a cd or dig a hole through it and then heal it. You could blow it to a full uncut cd cylinder. You can project the contents of cd using a viewmaster.

Just like in the movie Videodrome, you can insert a cd into an opening in your chest and act like a cd player. Similarly you could use a needle to play a cd, just like you would do with a vinyl record.