Sometimes a friend might need a little gold, and it can be irritating to trade with them if they're far away. I don't see too much of a problem with a /pay command in this situation? To pay mn614 20 gold, for example, it'd be something like /pay mn614 20, and then perhaps a confirmation gui with a checkmark just in case. I think it'd be so much more effective than using the local trading system, as you can use it whenever you want!