Although I have no real interest in the Pi myself, and am waiting for Olinuxino with BASIC on it instead, I`v come across something that may be neat for the Pi and users of other boards to have a go with.
I was given a broken old Amstrad Emailer, it`s like a fancy telephone really, and on there is the smallest little keyboard that still looks quite usable.
so I fixed the mailer enough to get some readings from the keyboard, and it`s PS2 compatible 
on the Inside of the telephone usint the keyboard lead terminates in a 4 pin plug.
Blue= +5 volts
Black= Ground
Green= Data
Red= Clock
the plug on the other end (the one that goes into the kbd), is, reading Left to Right with the polarity bump on the top;
Ground, Data, Clock and lastly +5v
I did a quick Google to see if there was anything to confirm this, and found this:
http://code.google.com/p/amstrad-mailboard/wiki/MailboardInterface
but this bit that may interest the Pi users is here; http://code.google.com/p/amstrad-mailboard/
so it`s perfectly possible to build your own Pi "laptop" now with one of these and a small 7" TFT screen! 
here`s a better picture of them with a Size scale:
against a 20:
I expect these things probably wouldn`t cost too much to buy second hand either, in fact I`v seen a guy on ebay selling them for the less than half the money shown in the above picture 
You would likely have to parse the keyboards data through a micro-controler or maybe some sort of linux program to get the correct ASCII code for each key, but that`s a fairly trivial task.
Have fun and let me know how you get on!
I`m going to try mine now on the DuinoMites PS2 connection and see what happens.
these could be a Great source of mini keyboards!
cheerio
