In July I got back to the UK after 10 months of wandering around the world: crossing Europe and SE Asia by train; some time in Australia, cycle-camping then living in Sydney for a while; and finally returning home on a cargo freighter (plus a train or two across the US). Having thrown in my nice sensible 9-to-5 job, I was supporting myself by freelancing, so going offline altogether wasn't an option. I needed to be able to check my email, keep an eye on my bank accounts, send in articles... And so I became GeekWriterType On The Road.
First up for consideration was hardware. For three months I was operating out of either a rucksack or cycle panniers, and carrying an eeepc 701. Major advantages: small, light, robust, and cheap (so less concern about theft). It's surprisingly easy to find power sockets (in train corridors, in station waiting-areas, in camp kitchens at campsites). In 10 months I was only asked to unplug once, by a security guard at Brisbane station, "because this is private property". Not what you'd call a reason, there... The extended-life battery I bought was well worth it, though.
While cycle-touring I developed a new definition of sybaritic luxury: lying in my tent with a cup of tea and a stack of chocolate biscuits, watching TV series downloads on the laptop. (After 60k on a bike in the rain, you really start to appreciate the little things.)
The downside of the eeepc is that the keyboard really isn't that great for typing on, even if you have skinny hands. My Mac (I know this is a Linux site but I really, really love my MacBook!) caught up with me in Sydney, and I switched back to it with a sigh of relief. Even then, I bought an external keyboard as soon as I was in the same place for a couple of months. Laptops are awesome in many ways but the ergonomics aren't great.
An ongoing issue was the need to find a net connection. Netcafes exist everywhere, but they often charge much more for wireless than they do for using one of their desktops. A USB key for file transfer was one of my most useful tools (and also provided handy backup!). When I reached Sydney (and later on when I was in the US), pretty much every cafe and hostel had free wireless access, but that's less true in Russia and SEAsia. Though my hostel in Xi'an (China) had both free wireless and a very pretty courtyard!
In Australia I got a USB broadband modem, initially with Virgin, but the service was bad to the point of unusability. I switched to Telstra: expensive but the connection actually worked. It was still slow compared to the connectivity I'm used to at home, but did work more or less anywhere within Australia. Including small coastal towns in Queensland – but not the coral island I camped on overnight!