3 for 2 on all Star Wars and Star Trek books.

Battle Surgeons (Medstar I) (Star Wars: Clone Wars) :: Michael Reaves, Steve Perry
ISBN-13: 9780345463104 - ISBN-10: 0345463102
Force Heretic III: Reunion (Star Wars: The New Jedi Order, Book 17) :: Sean Williams, Shane Dix
ISBN-13: 9780345428721 - ISBN-10: 0345428722
The Truce at Bakura :: Kathy Tyers
ISBN-13: 9780553568721 - ISBN-10: 0553568728
Dark Apprentice (Star Wars: The Jedi Academy Trilogy, Vol. 2) :: Kevin Anderson
ISBN-13: 9780553297997 - ISBN-10: 0553297996
Jedi Search (Star Wars: The Jedi Academy Trilogy, Vol. 1) :: Kevin Anderson
ISBN-13: 9780553297980 - ISBN-10: 0553297988
Dark Force Rising (Star Wars: Thrawn, Vol 2) :: Timothy Zahn
ISBN-13: 9780553560718 - ISBN-10: 0553560719
Heir to the Empire (Star Wars: Thrawn, Vol. 1) :: Timothy Zahn
ISBN-13: 9780553296129 - ISBN-10: 0553296124
Assault at Selonia (Star Wars) (Corellian Trilogy, Bk 2) :: Roger Macbride Allen
ISBN-13: 9780553298055 - ISBN-10: 0553298054
The Courtship of Princess Leia (Star Wars) :: Dave Wolverton
ISBN-13: 9780553569377 - ISBN-10: 0553569376
Splinter of the Mind's Eye :: Alan Dean Foster
ISBN-13: 9780345260628 - ISBN-10: 0345260627
Star Wars: From the Adventures of Luke Skywalker :: George Lucas
ISBN-13: 9780345260796 - ISBN-10: 0345260791
Star Wars, Episode V - The Empire Strikes Back :: Donald F. Glut
ISBN-13: 9780345283924 - ISBN-10: 0345283929
Star Wars, Episode VI - Return of the Jedi :: James Kahn
ISBN-13: 9780345307675 - ISBN-10: 0345307674
Showdown at Centerpoint :: Roger Macbride Allen
ISBN-13: 9780553298062 - ISBN-10: 0553298062

The Wrath of Khan (Star Trek) :: Jack B. Sowards, Vonda N. McIntyre, Harve Bennett
ISBN-13: 9780671456108 - ISBN-10: 0671456105
Star Trek Movie Memories :: William Shatner, Chris Kreski
ISBN-13: 9780061093296 - ISBN-10: 0061093297
Star Trek the Motion Picture (The Human Adventure is Just Beginning) :: Gene Roddenberry
ISBN-13: 9780671830885 - ISBN-10: 0671830880