a) Auto Glym Super Resin Polish (got a shitload for mum's car, but also works well on CDs, need bugger all and got a huge bottle).

c) Toothpaste - ONLY if the disc has deep scratches which render it completely unreadable. Can't remember which brand - don't recommend you try it unless desperate. Use toothpaste and then finish off with a really fine polish like the car polish I use above.
d) Sometimes I top off with a cheapo can of spray furniture polish...
Sounds mental, but I've had some classic (and hard to get hold of) games for my PS2 and PS1 back in working order doing that. Now I'm older I actually keep my DVDs / CDs / games in their cases at all times, but when I was younger I used to keep discs unprotected in my school bag
