...carboy brush for carboys? But past that...non-abrasive sponges?
If you're using glass carboys, you'll need that carboy brush. You also need a bottle brush, for your bottles and other narrow vessels.
Non-abrasive sponges and a soft nylon hand brush. Use a large bucket or a plastic tote for your starsan.
The most useful piece of sanitation equipment is a spray bottle for your Starsan working solution. Spray anything that can't be easily immersed. I always fill my spray bottle when I make a fresh solution.
other useful things on the list are:
bottle filler (plastic tube with spring activated valve on bottom)
hydrometer
hydrometer test jar
bottle capper
turkey baster or even better, a (wine) thief