Make Scratched CDs & DVDs Readable Again With Vaseline
Instructables highlights a simple tip for making CDs and DVDs with scratches readable again. Simply take a cotton ball and dip it in some alcohol to clean the area near the scratch. Then apply Vaseline or Petroleum Jelly to the disc. The Vaseline will fill in the scratch, hopefully making it readable again. One person in the comments noted that you may not want to use alcohol because it can damage the disc.
For step by step instructions please visit: Remove Scratches from a CD/DVD with Vaseline (Petroleum Jelly)