Another good idea from Elec. Although, it seems to me as though we're starting to design the worlds coolest compass/navigation aid.
As far as comuters go, it would be cool to have a computer that could be linked to a PC or laptop that could then email/link to the home computer to download recent info while on a trip and also access archived log information from a remote site. This would be proof of experience without haveing to carry a paper logbook.
Or how about enabling the portable unit that the diver uses in the water with logbook program installation software that would enable the diver to use an external keyboard to add details to the dive profile such as location, site name, dive buddy name, notes of interest and a rating system for the site.