Bring your own coffee. You won’t need your best beans. Any decent beans will still give you the nourishment you require for a bit of early morning (or late evening) coding. A coffee grinder and a French coffee maker is of course essential. If you plan to stay somewhere without electricity you’ll need a manual grinder and a pot suitable for open fire.
Also bring a computer that does not require a lot of juice. My current favorite is the 11″ Apple Macbook Air (MBA) with the added 60Wh from a HyperJuice external battery. That yields about 14 hours of computing time depending on what you do. This particular laptop has a 35Wh battery. Make sure you charge both when you get the chance. For longer periods off the grid you’ll need a bigger external battery. There are several choices available. Also remember to turn off Bluetooth and WiFi. Both consume power even when not in active use.
Locate the spots where you’ll be within reach of a 3G network. You may have to climb up high. Make sure you don’t fall over the cliff in excitement over new cool stuff you read about (like the new features in Eclipse Juno) when actually being able to connect. If you’re scared of heights stick to the low ground. Maybe you’ll find a 2G network.
It’ll be slow, but still sufficient for e-mail and the occasional Git pull/push.
Brace yourself for horribly long download/upload times. Now may be a good time for honing your coffee grinding skills.
The MBA does not have the hardware required for connecting to the cellular network. So my solution is to use my iPhone connected with the USB cable. The iPhone can also be charged from the HyperJuice battery.
And last, but not least; don’t forget you take in your surroundings.