Immortal Coil by Jeffrey Lang: The first book mentioned when the question of a good Data novel comes up. Chock full of continuity references not just to TNG but also to TOS, however, drawing a line from Roger Korby to Noonian Soong and establishing a vast Star Trek android saga. A saga that David Mack appears to have penned the next chapter in, recently informing us that his Cold Equations trilogy commemorating TNG's 25th anniversary ties back to Lang's work in a major way. All this combines to making Immortal Coil a key entry in the TrekLit canon, and one that many of us are revisiting right now - with The Persistence of Memory en route - or will be revisiting in the future.
The official blurb:
And the excerpt: Chapter 8.He is perhaps the ultimate human achievement: a sentient artificial life-form -- self-aware, self-determining, possessing a mind and body far surpassing that of his makers, and imbued with the potential to evolve beyond the scope of his programming. Created by one of the most brilliant and eccentric intellects the Federation has ever known, the android Data has always believed he was unique, the one true fulfillment of a dream to create children of the mind.
But is he?
Investigating the mysterious destruction of a new android created by Starfleet, Data and the crew of the U.S.S. Enterprise™ uncover startling secrets stretching back to the galaxy's dim past. That knowledge is coveted by beings who will stop at nothing to control it, and will force Data to redefine himself as he learns the hidden history of artificial intelligence.