Anna Karenina is one of the best books I have ever read. Recently I also read "Reminiscences of Tolstoy" (published by Sparkling Books). It's a biography written by his son Ilya Tolstoy. I really enjoed it: it reveals very interesting details of Toltoy's personality. For example it seems that Tolstoy's wife has written passages of Anna Karenina and corrected her husband's grammar.