I don’t read as many Star Trek novels as I once did, but courtesy of the local library I just finished Ex Machina, by Christopher L. Bennett. It’s an original series novel set during the time following the events of Star Trek: The Motion Picture (ST:TMP for short). Mr. Bennett has chosen (wisely, I think) to treat the much-improved Director’s Edition of the movie as the definitive release.
In many ways the book is a direct sequel to the TOS episode For the World Is Hollow And I Have Touched The Sky, but the author takes uses this particular timeframe to explore the changes the crew has experienced since the end of the original series, and their various reactions to the rather spectacular events of ST:TMP. He also works in an unusually subtle (at least for a Star Trek plot) subtext concerning religious fanaticism and terrorism, with obvious parallels to current events. I know, I know. That sounds like a sure-fire route to preachy and heavy-handed editorializing, but to the author’s credit it actually works surprisingly well.
The book is also packed with plenty of interesting and obscure references to other Trek episodes, as well as a number of passing retcons aimed at explaining onscreen inconsistencies and peculiarities. All of these are helpfully noted and explained in the Star Trek: Ex Machina Annotations the author provides on his web site. That’s a nice touch.