ah, the home office
Even if I didn't work from home, I'd need a home office just to handle home affairs! So I have a table in the dining room with the printer, scanner, phone, Airport base station, inboxes, etc, and a wooden 3-drawer filing cabinet. Oh, and a good task chair -- do NOT skimp on the task chair (any more than you would skimp on the filing cabinet), or you will come up with any excuse to avoid doing actual work at home. Trust me.
The "portable" parts of the system, that go with me from home office to work office, are my laptop and a pair of Levenger travelling inboxes (nylon zip holders). One holds project support material and my "to read" stack; the other is my travelling tickler file.
If you have a computer here which does not get backed up in your work office, some thought to a backup system will save time and aggravation later. I have a FireWire drive which plugs into the laptop, which uses Retrospect to back itself up nightly. Since I have a Mac (and I believe in redundancy when it comes to backups), I also back up key files over the net using .Mac.