To extend on Jfish's post.
Soldiers in the US Army carry Ipod Touch, LOTS of them. They carry Iphones.
Are they perfect NO, not hardly; but they do pack lots of useful tools in a very small space.
Gun sites, GPS, translators... the things are darn near Tricorders....
Another option not mentioned would something more robust, like an OLPC. not ALOT of power, but a full out PC with a keyboard. Plus, can be powered from darn near anything- AC/DC Solar/Crank......
Selling on Ebay for 100.00 used.
example (not mine, no money etc)
http://www.ebay.com/itm/OLPC-XO-1-Excell...=item19cf1f5e10you can carry alot of files on a 1GB Micro Card....