Currently the coins are only used in shops. To purchase/sell graphics.
My suggestion is that we could use them to buy other things as well as this.
Such as your own custom rank, different coloured name, name change
etc. These are ones I've seen on other forums. Each would cost a certain amount of coins.
I'm not sure if it's possible to do on forumotion but there's bound to be some code for it or something somewhere.
Post your opinion.