The Nokia N810 internet tablet has a built-in keyboard, can be paired with a bluetooth keyboard, and has an 800 pixel wide screen. It's super-light-weight (<0.5lb), can be charged from a solar panel, and the battery lasts for days on standby, 8+ hours on light/normal use. Also, they're relatively inexpensive lately (<$200). Great choice for lightweight text input, internet browsing, etc. (as long as you can find WiFI, or you can pair it over bluetooth with a phone w/ a data plan).
Alternately, and even smaller/lighter, is the Nokia E71, an absolutely smashing phone:
http://www.boygeniusreport.com/2008/...ia-e71-review/
QWERTY keyboard, phone, can run office apps, do email, internet browser, GPS. If you're bringing a phone along anyway, why not make it a miniature computer? Super lightweight compared to all other options (esp. since there is no need for a secondary phone), very long battery life. You can also use a bluetooth keyboard with it if you're concerned about touch typing.
Downsides: 320 pixel wide screen.
I used an N810 on my last trip as a travel computer... next time I'm downsizing to an E71, I'll let you know how it works out
Sam