Add to existing lists:
Toolkits - one larger one (power screwdrivers always good) for server room work, one portable one for taking around to PCs. Never mix them and you will always have the tool you need at hand
Filing cabinet - good for manuals, printouts of receipts, license agreements, etc.
Cable management and patch panels are a must - start your room out with everything going to patch panels and your life will be easier in the long run when you add to the system.
And lastly, take the time to set it up right the first time - what others have mentioned about spacing the racks, tables, shelves apart, cable management, etc. If you start out with a complete wreck of a room, it's probably going to just get worse over time.