I actually spent some time looking into dumb phones a couple years ago. My favorite would be the motofone. It's got an e-ink display, which is great for battery and sunlight, and 2 antennas which is also great if you heaven forbid make actual calls with it. Also, pretty sturdy, small, and light.
http://en.wikipedia.org/wiki/Motorola_Fone
Beware though, if you txt a lot, you won't like it. Not enough real estate for the crazy font they use.
There are also these printed cell phones showing up. Do a google for "card phone". Pretty interesting.