First time I've even seen one of these:
That UA's the original, pre-color Nook, and problematic for us Mozilla-required white-listers.
Ironically, the current Nook Color's UA includes Mozilla, not Nook --
Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_5_7;en-us) AppleWebKit/530.17 (KHTML, like Gecko) Version/4.0 Safari/530.17
-- and that UA's problematic for network admins and others "because it identifies itself as a Mac OS X desktop...". [bookclubs.barnesandnoble.com