Get water or a beverage while working without having to clean up or track dirt/grime/grease through the house.
A decent sound system is nice because it just sounds better than the cheapy while listening and working. Plus, you can get the news without going in.
Don't forget the Comfy Chair. When you're bummed out, or need ideas, a short sitdown can help. Make sure the covering is easily cleaned, and bonus points for an earthquake shaker installed and set to go off after 10-15 minutes so your a$$ doesn't stay in the Comfy Chair too long.
But most important - keep it clean, and set it up so that your work pattern is sensible. Nothing like walking 25 feet 40 times a day to grab something else out of the toolchest.