The Rise of Vader
It didn't take long for the Extended Universe to pick up after Revenge of the Sith. Just released, Star Wars: Dark Lord - Rise of Darth Vader purports to follow the exploits of Vader immediately after his birth and demonstrate how he earned his reputation. I'm a lot more intrigued to read this stuff than the (albeit excellent) Labyrinth of Evil, the lead-in to ROTS. Probably because we've never been told the story of Vader in-between episodes III and IV, the last remaining hallowed canon ground of Star Wars. Also probably because I'm quite the fan.
Via The Force.net