But seriously, you will need 220V with GFCI, and several 120V outlets, with GFCI.
Good lighting. Good ventilation.
Tile Floor with drain.
A sink would be handy, and at least have it able to hook up to a garden hose for instant washing ability.
I'd mount a stereo with AUX input for MP3 player, or native MP3 support.
Wi-Fi is very handy or run CAT5e if you want pure connectivity. This will allow you to not only surf HBT while you brew, but you can also host a brewcast online as well.
Comfortable an portable chair or several if you have friends over.
Grill just outside the brewshed.
Bottle openers. Lots of them. Nobody wants to walk 3 feet to open a beer.
Beer fridge.
Shelf for beer glasses.
Dual stage ferm chamber.