Ok so obviously I'm interested in my "special" case. The site D2jsp, uses it's own currency and follows similar rules to the ones posted above. I'll link a few as example.
These rules are taken DIRECTLY from the sites Official Forum Rules and Policies. These rules will not appear as they do in this order on the forum, but they are direct quotes.
Selling anything for money is not allowed. Bannable on the first offense. This includes, but is not limited to, selling items via paypal.
Multiple Accounts: You may have and maintain one, and only one account on this site. Multiple accounts are not allowed. If it is found that you have multiple accounts that you are using, or sending gold between, or posting on your own topics with, you will be punished for it, up to a possible banning of all of your multiple accounts.
Forum Gold: We allow you to trade and exchange gold with other users of the site, i.e. give your gold to someone else. You are not allowed to beg for gold, threads begging for gold will be locked and warnings issued. Be creative for ways to compel people to give you their gold. Begging for gold is not allowed. You are not allowed to sell forum gold, under any conditions.
Advertising for Money: You may not, under any conditions, advertise for commercial purposes any product or service. This includes, but is not limited to, selling items, accounts, any information, scripts, etc. You may not post links to referal sites, or any other revenue producing links. Failure to comply is bannable on the first offense.
Buying or Selling Items/Services for Money: You may not, under any conditions, buy or sell any item or service from or through this website for real money. Failure to comply is bannable on the first offense.
No links to auction sites selling D2 items, or any other website that sells D2 items for money. Links will be removed and an official warning issued. Subsequent offenses will result in a ban.
Purchasing - You may Buy Forum Gold directly from the site (njaguar). Please click here for more information: Purchase Forum Gold.
Selling - You may not Sell forum gold for money to anyone. Only njaguar has this right.