There's an old trick you can do to salvage dented ping pong balls. You put it in boiling water, the air inside expands, and the dent magically disappears. Here's an even cooler, albeit more time consuming and skill intensive way to make use of the damaged goods.
You can always count on Japan to bring us cool stuff in miniature form - I'm looking at you Hi-Chew candy; it's impossible to pack that much flavor into one tiny piece of candy, you manage to do it though. This Death Star is made using the aforementioned ping pong ball and some card stock. The rest is done by using an ancient Japanese technique akin to "the force"... or paint or whatever, I dunno. Check out the pics and behold its glory. Just don't leave it around the cat.
What other movie props/set pieces would you like to see carved out of ping pong balls?