There are currently 3 assorted Spanish-language Random House Mexico titles free in the B&N store, which may or may not be glitch freebies.
It's a mix of 2 apparently self-help parenting/health books and 1 thriller novel.
I'll just link you to the
post with the links and descriptions over @ the Free NookBook Summary Blog, which is where I found this. They also have a nice sidebar link for all the currently still-free Nook stuff, should you have missed any earlier, and are a very handy way to keep up with most of the B&N-available freebies.
Enjoy while it lasts, if you happen to read or want to learn to read Mexican Spanish.