Here you go, here's a list of the books:
http://en.wikipedia.org/wiki/List_of_Star_Trek_novels
Not counting Blish's numbered books because they were episode adaptations,
Spock Must Die! was definitely the 2nd original novel after
Mission to Horatius. I also have
The New Voyages and
Planet of Judgment, but they're 1990s reprints, not the originals.
TMP was what opened the floodgates for the Pocket Books novels. Man, that was the start of an awesome run of Trek books that, sadly, has now ended. They're even holding back reboot inspired books so that they don't contradict the sequel to the 2009 movie. As an avid reader, that really makes me mad.
