The Optimus keyboard is pretty awesome, with remappable displays under the keys. But it'll cost as much as a "good mobile phone". Probably $500+
I'm starting to get RSI in my hands. The Natural keyboards alleviate that - but I can't find a Mac layout, USB natural keyboard. Plus, I don't like the random buttons on the top of most Natural keyboards.
There's a company that sells unprinted keyboards, but not natural ones.
I suggest a new marketing strategy for keyboards: a company sells personalized keyboards - you can select what keys are where - for only $5 more than everyone else sells keyboards. They have several form factors - regular, natural - several base keyboard layouts per language - Mac, Windows, Solaris, and several options about having the custom buttons at the top.
Kind of keyboards, on demand. I'd buy one.