The Darth Bane Trilogy
Bane trilogy explains how the Sith’s rule of two came into being. This series consists of three books: Dynasty of Evil, Path of Destruction, and Rule of Two.
The Unifying Force
This is the last novel in the New Jedi Order series, and has been quite popular in the United States. It featured for the first time Kyle Katarn from the Dark Forces and Jedi Knight games. The book indeed works as an epic finale for the New Jedi Order series, with an amazing galactic war.
Shadows of the Empire
Shadows of the Empire was introduced between The Empire Strikes Back and The Return of the Jedi, presenting a new villain, and explaining how Luke, Leia, Chewie, and Lando got to where they were at the beginning of Return of the Jedi.
It was bound to happed: a Star Wars-themed zombie story. This is one of the only such Star Wars books. It features Han and Chewie fighting a whole Star Destroyer full of Stormtrooper zombies. A sequel, set in the Old Republic, was recently released. Brrraaaaaaiiiiiiinnnnnnnnnnnsssssssss!!