You can buy spanish ebooks in
www.mobipocket.com although I think only in mobipocket format. Spain is still way behind in promoting ebooks and ebook reader, I haven't seen any ebook reader yet, although they do sell it in Mediamarkt, There's no real marketing effort from their part, I've seen it exposed, next to mp4 readers and stuff like that, without further explanation, someone who does not know what it is won't even look twice.
anahid