You should see the KeySonic nano keyboard (ACK 3400U) - it's SO cute. About as thick as the 770 (without cover), barely taller, and some 50% wider. Short of the foldable BT stuff it's probably the best match you can think of - right down to the matte black finish. And it's a *real* keyboad, albeit petite - not something you'd want to write "War and Peace" on, but definitely beats anything on a PDA, past and future :-)
(must remember to snap & post a pic...)