It would be really handy if, when I am buying something from a vendor, it would show how many of that item I already own.
Also, the Max button is too close to the + and I often click it instead of the Buy button, because I expect it to be, well... a Buy button. Could the Max button be moved down, or something... perhaps in a box that says "Max you can purchase = x amount for y currants" or some such.