Concept device for programmers

I have to travel a lot to the subway (courses, study), so I lose a fair amount of valuable time, so, during one long journey I remembered the device for working with e-mail , and then the idea was born to do the same but only for programmers, those. Something like a PSP, but with a convenient coder keyboard, and with a display in page format. Using such a gadget, it would be possible to type pieces of code during the road, and at home, by connecting to a computer, transfer it to the development environment and compile / check for errors. I think it would be good to pass the time well. What do you think?
PS laptops, netbooks in the calculation do not take, because can not use standing