Even though it's sort of an aside, I'm glad someone mentions Psion. I'd love to check whether their keyboards are on par with the legend. I wonder how many others relate, at the global scale :)
Since then, dreamed of some comparable device, basic linux, enough for vi and terminal stuff, wifi/bluetooth and well, happy with the screen. Alas all devoplment of anything close, tend to wack in CPU's that would be classed as a supercomputer of the 5MX time, power hogging colour screens and you end up with devices that will last a day perhaps, but not the month the 5mx would pull with comparable usage with the rs232 adapter.
Hence a cheap terminal, basic local editor wifi device in that form factor and if it could do bluetooth and double as a keyboard for a smartphone, well, a simple device like that would tick my boxes and maybe many others.