I've used T cut and it works but only had to do so once (On a bad scratch) Im a freak on keeping my CDs in mint condition.
Another thing I've tried with great results is to clean or should I say polish my
finely scratched Cds with Mr Sheen furniture polish and a very fine soft cloth
The procces is as follows:
Sparay onto affected disc, lightly spread around surface and leave for about 30secs
this enables the polish to loosen any dirt/muck.

Take soft fine cloth and start rubbing the most critacal areas of the scratched CD
in a outward direction (Centre to edge) and then finish off by simply polishing off
the rest lightly.

I have found this to work on bad scratches too, the polish doesnt completly remove
the scratch but instead smooths off the sharp edge of the scratch which actually
causes the laser light to refract from the disc which cause the famous repeat.

I must point out that you should only attempt this on a hard flat surafce and not rub
between your fingers, this can cause distortion and warp your discs

Happy polishing, it works well for me everytime

Last tip:

If you do have a PC with a writer then backup all the IMPORTANT and popular
onto your Hard drive so that when your CD does give up the ghost you still got
your important tracks BUT remember to keep your Dead CD as proof and never
play Mp3s from the net at gigs as this is sure to draw attention oneday and you can
say good bye to everything connected to your rig/stack/system etc if busted.
Besides artists need our support to keep the music flowing.

Submitted by Chrismk - DJ's United Forum