The Essential Deep Space Nine Relaunch
Probably the best series of Star Trek books have been the relaunch of DS9 as an 8th season in book form. They began in 2001, two years after the show aired it’s finale. The post-finale DS9 book universe is the most realized. They are (for the most part) well written, fun, dramatic and often compelling.
TrekMovie.com has posted an essential run down of the new series. They pick the absolutely indispensable books for those considering picking the series up. Enjoy! Link.
You can also find info on the DS9 relaunch at Memory Beta. Link.