I've just finished The Eyre Affair by Jasper Fforde. 5 stars all the way.
What a cool idea! Very interesting and novel way to look at the book world. In Fforde's universe, books are the popular culture. Authors the celebrities, and Shakespeare the Frank Sinatra of the modern world. People have been arrested to putting on their own interruptions of his works, and the Friday night date is a play and dinner.
You've got alternate history, a time-traveling father, cloned extinct animals, and a genius uncle who invented a machine to enter books. Literally. You can enter a book at any point in the narrative and explore. As long as you don't mess with the actual storyline.
The best thing? There are sequels! Lost in a Good Book here I come.