The ESV Bible Blog has posted the results of some number crunching based on searches that have been run for specific words and verses. The results show a definite preference for the books of the New Testament:
This last chart shows how popular each book is when controlling for the book’s length (the Psalms get more views than Jude in part because it’s a much longer book). The most popular books by this measure are Ephesians, Philippians, and Romans. The least popular books are Ezekiel, Jeremiah, and Hosea.
I guess that’s not surprising. Who wants to read 3,000-year-old rantings from a bunch of angry old men?