Say I play World of Warcraft and I kill a boss and get an item worth 10 gold. If the fair market value of that 10 gold is $5, do I have a taxable gain of $5? (As I understand it, the answer in the United States is "nobody knows".)
I would guess the IRS isn't interested in WoW gold. Although that might be a mistake on their part. Some people have made a lot of money off of Chinese sweatshops that play WoW and rake in the gold...