Song of Songs is one of few books in the Bible that doesn't include the Big Guy (i.e., God) as a major player. It's a notable absence, don't you think? Check out the Book of Esther for another book sans God.
Song of Songs refers to 21 species of plants and 15 species of animal. It's a veritable biblical menagerie! Botanists and zoologists, take note. (Source)
Song of Songs may not have been written by Solomon himself, but the book appears to be dedicated (or aimed) at his cultural legacy. Kind of like a presidential library.
Attention linguists! Almost fifty words appear in Song of Songs that do not appear anywhere else in the Bible. Now that is cool. (Source)