The more you leave the office and still work, the more you must plan ahead to make your work tools mobile. ComputerWorld's Office in a Bag lists many of the items some mobile professionals feel are musts for the modern digital nomad.
What one person feels is important may not be what you feel is important. The goal is to help you work more comfortably when not at your desk. Almost every list like this puts a USB or wireless mouse toward the top of the most important items. You may be perfectly happy with your track pad. If so, don't worry about buying a mobile mouse just to keep up with the digital nomad Jones's.
I liked the HP Officejet H470 listed. I didn't know about this particular mobile printer, although I knew HP has been making mobile printers for year. But 1200 dpi color printing for around $250 street price is a pretty good deal. It supports all major operating systems: Windows, Mac, Palm, Windows Mobile, and Linux.. Sounds like you could almost hook up your watch to the printer and get pages.
Every list like this mentions a couple of portable USB hard drives for your laptop or netbook. If you need extra storage, these are a good idea. If you use them for backup, also backup over the Internet back to your office or a hosted backup service. Digital nomads run the risk of having equipment lost of stolen. When your only backup is in the bag with the laptop, digital nomads get depressed. Plan ahead for your backup and be a happy digital nomad.