While a diamond may be forever, your optical media are not. Your CDs and DVDs may seem permanent, but after just a few short years they can start to lose data integrity, whether because of surface scratches, problems with the dyes used in manufacturing, or other troubles. If you've got important data on there, you want to be able to get it back, so you need a tool that can handle the job.
CD Recovery Toolbox is designed to help you with that task. Feed it a bad disk and it will do its best to recover the maximum amount of data possible. After it's scanned your disk, it will tell you which files are recoverable, and make sure you've got room on your hard drive to bring those files over. And even with files that aren't totally recoverable, it works to grab the maximum amount of data possible—and it's better to have some of something than all of nothing.
A free download, CD Recovery Toolbox is a Windows application. It will run under Windows 98/NT and later versions.