In the “Not strictly required, but really useful” category:
- Compressed air
- Magnifying glass or magnifying glasses clip-on
- Pendent or mini-keyboard for jogging
- Good wrenches for your spindle
- Extra lighting around the machine
- At least one extra power receptacle near the machine
For the last, I regularly use my palm sander while work is on the machine, so a nearby place to plug it in is useful.