I use a product called Lift Off after I found Goof-Off to be too harsh to plastics. Here's what it did for my Final Fantasy VII.
Just found it out today and so far so good. Just never let the stuff touch the bottom of the disc. It can eat away at it.
Isopropyl will do exactly the same with no fear of causing damage to the underside of the disc though, so why take chances?
i use a very tiny amount of nail polish remover. so tiny you can see it vaporize. it is very abrasive if you leave it on for a long period. this works on glossy box surfaces, plastic wraps for sealed games, etc. just remember not to put so much.
Metho works (very small amount, mixed with water), also just plain water and CD cleaner works as well.