This kit from Datawrite actually does what it says on the tin (or rather, packaging)- it repairs your CDs and DVDs if they have scratches on them.
How does it do it? Very simple- the solution is designed to polish (very finely) the surface of the disc and in doing so smooths out scratches. Despite their negative effect on the drive's laser (due to scattering its light in the wrong direction), most scratches are very superficial and can be removed with minor polishing using this solution. No hard work, and no damage to your discs- quite the opposite in fact!
Comes complete with a disc-friendly cloth.