You could use them for drinks coasters - hence the term 'coaster' for a CD that failed during writing.
As Hemispasm says, you can't reuse the discs. However, it may be enlightening to try to work out why you got a buffer underrun - modern drives invariably support some kind of buffer underrun avoidance technology, which makes it very hard to finish up with a coaster from buffer underrun.
It may be worth checking that such an an option to turn on that drive feature in your software is enable - if it's exposed to the user (it is in Nero).
If you post details of your drive and software, we may be able to advise you further.