Every year since I started blogging in 2007 I have listed a different set of five books on my Profile as my favorite books (not to be confused with Recently Read Books). The categories are, well, Shakespeare (Othello, King Lear, Macbeth), American Classic (The Scarlet Letter, Moby Dick, The Great Gatsby), Enduring Classic (L'Etranger, Waiting for the Barbarians, In the Lake of the Woods), History (Hell In A Very Small Place, Black Hawk Down, Breakout) and Biography/PoliSci (Growing Up, U.S. Grant Personal Memoirs, Goodbye Darkness).
This year I'm listing Hamlet (Alas Poor Yorick!), The Adventures of Huckleberry Finn (how did Huck miss the Ohio?), The Catcher in the Rye (Goodbye Holden!), Plagues and Peoples (nature will win) and Sherman: Fighting Prophet (you'll discover how and why the Union won the Civil War in this excellent biography).
You can tell a lot about a blogger from his or her Profile.