Seriously, some people have characters who are specialized in finding gold. The typical gold finder is a barbarian who is MFing in nightmare Travincal to kill the councils. Check the barbarian forum for details.
You can get sometimes pretty good stuff from gambling but you need lots of gold and you can get it easily in Hell with a good GF, even the lowest monsters drop thousands of gold with a high GF.
I think gambling is the only reason why people need GF%, repairing of armors etc can be done with runes instead of money.