According the New York Times [2] and Publisher's Weekly [3], the best selling title is James Patterson's Tick Tock [4]. Where do you find that information? On our library website, of course! If you haven't visited the Books [5] tab yet, it is a great resource for all bibliophiles!
Links:
[1] http://hcpl.net/users/gwendolyn-m
[2] http://www.nytimes.com/best-sellers-books/overview.html
[3] http://www.publishersweekly.com/pw/bestsellers/
[4] http://catalog.hcpl.net/ipac20/ipac.jsp?menu=search&aspect=subtab13&term=james%20patterson%20tock%20tock&index=.GH#focus
[5] http://www.hcpl.net/read/books
[6] http://hcpl.net/category/tags/tick-tock
[7] http://hcpl.net/category/locations/northwest
[8] http://hcpl.net/category/branches/reference