I've just put together a mobile computing and gps setup for my forthcoming trip to Romania, and am surprised by how easy and cheap it now is. The kit comprises of:

Palm M515 colour handheld computer (now slightly obsolete) which can be had for as little as £160.

Palm folding keyboard (like a laptop keyboard, but folds up) - £30

Magellan Companion GPS with European maps (plugs into the back of the Palm) - £120

Magellan car charger cable (charges Palm and GPS at the same time) - £20

Palm bluetooth card (allows wireless comms between Palm and phone) - £40

Ericsson T68i tri-band bluetooth phone - £60 with an Orange contract, but quite low world-wide tarrif.

For email and web browsing, i have the free Eudora. MSOffice compatible wordprocessing, spreadsheet and powerpoint came with the Palm, along with all the usual organiser tools. I also have a sophisticated database (have written a fuel use log program on it), and an image viewer. The next additions will be a digital camera (with SD cards, which work with the Palm), blogging software, and some means of mounting it on the bike (probably just in the map pocket of a tank bag).

There is also sofware available that allows the more detailed Touratech maps to work with it - see http://pathaway.com/

It's a cheap, light and extremely versatile system. The only downside is that it's not waterproof.

Rob