I'm a US citizen who bought a 6000 from Amazon.com and then brought it back to Europe with me. I really don't even think of traveling around Europe without my Z.
You'll likely want this software:
Kismet (backend and GUI) - on "all international" setting finds tons of hotspots
Ubahnnav - an essential public transport planner for major cities
KO/Pi - for a robust email client (IMAP etc.) and PIM
FXconv - currency converter
Zplayer (and Mplayer backend) - for listening to audio and watching videos on the road
Zbedic (and related dictionaries) - for translation
DMblogger - for keeping tabs on RSS feeds, with an option to download full posts and save them for later
Camera assistant - for congfiguring your camera settings for that perfect photo
and this hardware:
Wi-Fi card - if you don't have a 6000. A dial-up modem adapter seems a bit retrograde and impractical
USB adapter - to link your digital camera to your Z and transfer pictures for more storage (and boring slideshows)
SD/CF cards - with tons of space, just like MB Zaurus said. Buy.com is presently selling a Kingston 1GB SD for something like $40.
simple plug adapter - sold in any Radio Shack for about 99cents
I don't know if I'd ever take backup copies of the ROM and ipks; but to repeat MB, I would make sure that everything is running smoothly beforehand. And I
would not ever start tinkering with my Z on the road. If it ain't broke, don't fix it (until you get home, of course.)
For finding hotspots, you'll want to visit the following sites beforehand. I wish JiWire had a compatible online/offline hotspot finder for the Zaurus - its AvantGo channel doesn't work.
http://www.wifimaps.com/http://www.jiwire.com/http://www.a2b.cc/http://www.wi-fihotspotlist.com/I think you'll be surprised how many wireless networks are free but unadvertised. I pulled out my Z in a coffee shop in Heidelberg and scanned with Kismet and found one. The barista later told me they had an open WLAN but didn't make a point of telling everyone. The tech-heads and the regulars would figure out soon enough.
As for the Z becoming a life project, I could easily see how that could happen. But I've managed to get by by sticking with the stock Sharp ROM and adding just enough apps to make my Z indispensible without spending days on customization.