I use a combination of a Logitech G11 keyboard and G13 gaming pad, which gives an obscene amount of assignable/programmable buttons. You could probably argue that the G13 is totally unnecessary for a game like UO, but I find it an awesome piece of kit that ensures my normal keys are all kept just for chat.
Not sure if they still make the G11, but here is the G13:
I assign ctrl/shift and alt to the buttons south and west of the mini-joystick, effectively giving you up to 66 macro combinations excluding the joystick. In addition, you have buttons to switch between three keyboard layouts, which I use for different mage setups. The LCD thing at the top has various functions, but I tend to use the countdown timer which is good for Siege ROT and stuff like that.