Usopp's long nose

It is possible that Usopp's long nose was inspired by the fairy tale "Pinocchio", as Pinocchio was a wooden puppet whose nose grew longer whenever he told a lie.
Usopp's personality could also come from The Adventures of Baron of Münchausen, who said he had traveled around the globe on a cannonball, a lie Usopp himself said in episode 19, though no one gave any attention.
"The Boy Who Cried Wolf" is a story of a boy that often tells lies of an impending wolf attack in order to gain attention, much like Usopp lies of imminent pirate attacks. When the wolf actually did arrive, no one believed him. This story was written by an author known as Aesop. The word "uso" means "lie" in japanese. It is possible these two instances are the influence behind Usopp's name.