I think there should be a bank that we can put our forum gold in or a stock market to play on within this site.
For the Bank, if we deposit our gold in there, we should be able to get interest on it over time. Like monthly interest of something. Interest rates could be different based on how much forum gold we deposit into our bank. You could also have mods set a limit for how much you can withdraw per day (upon your request) so that you don't go over your budget or something. If you absolutely need more forum gold than your limit is, you could pm a moderator and tell them what it is for, (like if you have a trade set up already and ready to go through, he could allow you to exceed your limit for that purchase or something)
maybe the limit thing is too much, but the interest thing would be cool like a real bank.
The stock market could be based off of the current stock market and users could invest our forum gold in stocks (1fg = $1 irl on the stock market) and we could buy shares of companies and our investments would go up or down based on the real stock market.
These are just two ideas that I had.
Let me know some feedback.