I just
answered a question about buying the nook version of Cold Days from the store, and having examined the store myself I saw that the B&N link for the Hard Cover contains a button for the nook version as well.
However the B&N link in the "Kindle Edition" section of the store is broken, for predictable reasons... So
my suggestion is to replace the "Kindle Edition" section with an "e-book" section that has the B&N link from the Hard Cover section.
This may be a minor, rather superficial change that only has the intention of remeding some user ignorance, but I can tell you from my own perspective that it would easily make
the difference between some people buying Cold Days e-books from the jim-butcher.com/store rather than from their nook interface. (what I have been doing up to this point, dispite using the website ASIN switcharoo trick for random amazon purchases)