I'm a big fan of Russian classics so I recommend, if you haven't read it, something by Dostoyevsky (my favourite is Crime and Pinishment, but he's got so many good books).
Also, if you can get your hands on him, he's the most famous Icelandic Writer Halldór Laxness. I read one book by him (Under the Glacier) and it was great!
also, i've studied Scandinavian literature so I could go on forever about that, but I don't know exactly where your interests lie and what you have read. i guess you can make a Goodreads account and fill it with stuff you've read and link it here so we can see what to recommend ^^