And somewhere to keep it cool, but yeah, that will get you serving beer from a cornie.
However, once you get a basic cornie setup the urge to upgrade is not far behind.
Pretty soon you have more than one cornie. Then it's a regulator and large gas bottle, so you don't have to muck about with bulbs and manual co2 charging. Then it's a co2 distributor so you can supply gas to more than one keg at a time. Next thing you know you are fitting flow control taps to a dedicated beer fridge.
I should mention that you won't regret any of this, it's just that you should be aware of what will happen.