The money mod adds two important mechanics to the game:
Custom currencies - Instead of using diamonds for trading, you can use the currency printer to create your custom currency. You can even choose if you want the ability to print more or not. While technically a work in progress, this feature is mostly complete and should work on multiplayer.
Stock Market - In order to get investment in an idea of yours, like constructing a supermarket, you can use a Stock Exchange block to list a business, and collect any income you recieve from other people buying your stock. You can either have it be traded in a currency, or an item like diamonds. This feature does not properly function on multiplayer and may still have some bugs even on singleplayer.
