Easy Money
To earn money easily(if you have at least level 3 guile, preferably even higher) go to a shop that will give you good prices on an item (for instance, the item shop in Knothole Glade with gems) and buy all of the items if they are at a good price (if price is written in green, then it is a good price), Then sell them back all at once, and if you make a profit, you can repeat this process as many times as you want to make big money, if you save up a lot of one item (such as several hundred, or even a thousand diamonds) you will truly see how this glitch can be useful.

Burning Swords
Euip a sword, cast the multi strike spell, and then go to the menu and hit equip again on the same weapon. Then go to a store and buy/sell items for a little while back and forth, then exit and see if the sword is glowing like crazy, if not try buying/selling some more. Once the sword starts glowing it will appear to be on fire, and sometimes there will be so much that you can't even see the blade.

Money from Houses
If you buy a house, put up a trophy, sell the house, take the trophy back, and repeat, you can make decent money from the house, earning the trophy's value in profit each time you sell the house. Also you can kill(or luer away) everyone in a town and buy there houses (if you have the gold) and rent them, after a few days the new villagers will appear and they will start leaving money outside of the door for you.