Webster's has a constant influx of new books thanks to the students, faculty, and other highly educated people that populate the area surrounded Penn State. While it's not tidy (books can be stacked up all over the place), Webster's has a great selection in catagories such as literature, history, science, philosophy, psychology, and more. They have a "room" that is dedicated to children's books that is particularly fun. They will also buy your books (either giving you money or trade (more books!)).
They also make a mean iced coffee at their "cafe"-- and sometimes their workers are particularly yummy as well.