2-Piece Split Keyboards
List of ergonomic keyboards that are in 2 physical pieces.
From more expensive to less.
Note, this page is no longer being maintained, because as of 2018-12-15, there are too many of them.
Keyboardio
Diverge
Ergodox
Ultimate Hacking
Kinesis Freestyle Edge
Matias Ergo Pro
Mistel Barocco
Goldtouch Adjustable
Kinesis Freestyle
see also Best Ergonomic Keyboards, Xah Pick