Some strange keyboards listed here...

[elecplus]

This is from a typing injury and keyboard alternatives site from many years ago...
http://ftp.tuwien.ac.at/faqs/allfaqs/co ... ards/part1

Some of the things I have seen bantered around, like keyboards with "snap on" attachments or rearrangements, were apparently built at one time.

[Findecanor]

I suspect that it is this FAQ that lives on at www.tifaq.org.
There are some nice very old images in its archive.