I have a separate work space in the backyard, an entirely separate building with a view of some flowers and plants, and a door that locks. Walking to work (about 12 feet from the house) and closing the door behind me does wonders for my focus and productivity.

Worth over-spending on a quality chair that fits and can adjust, too. I tried a dozen or more until I got the right one and it's been money very well spent. Don't skimp on the ergo!

I just recently got a rolling tool chest from Home Depot with a lot of somewhat shallow drawers. Perfect for stowing a laptop, laying out pens and pencils in neat order, and other miscellaneous cruft. The whole thing rolls (quite heavy though) and plugs in to the wall with a surge-protected outlet strip built in. Put the laptop on the top and it's a reasonable standing desk, too.