I've read very little Trek sci-fi, or other tie-ins for that matter (no snobbery, I just save my reading time for new settings I don't already get a dose of from TV).
Current/recent reading:
- "The Amazing Adventures of Kavalier and Clay" by Michael Chabon - story about a fictional pair of comic-book creators working during the birth of the Golden Age of US comic books; an interesting insight into the period, good story, and a brief appearance by Stan Lee!
- "Carter Beats the Devil" by Glen David Gold - fictional account of the career of Carter the Great, a 1920s stage illusionist; a superb read, combining fascinating facts about the great conjuring acts of the early 1900s (such as Houdini), the mysterious death of President Harding, the invention of television, the nature of illusion, romance and a great story to pull it all together. Highly recommended.
- "Dead Air" by Iain Banks - the complicated life of a London shock-jock post 9/11; good, though not a patch on his earlier stuff like The Crow Road, Espedair Street.
- "The Tipping Point" by Malcom Gladwell - a study of how social phenomena work like epidemics, and how the snowball-effect can result from a very small change; read this book and see the world around you just a little differently. It's fascinating, full of good examples, and very convincing. Bound to be in every would-be demagogue's back pocket...
- "The Second World War" by John Keegan - a cogent, easily-digestible one-volume history of WW2; an excellent overview if you're looking for a comprehensive history that'll identify areas you'd like to explore further. As always, clearly written, lucidly argued.
- "Redemption Ark" by Alastair Reynolds - set in the same universe as his first few books, about humanity's first encounters with a machine intelligence whose purpose is to wipe out all intelligent life; not a new idea, but very well presented, and with a few new twists. His SF is diamond-hard, but he also does decent characters too. Read this, and the first two as well!
- "The Dragon Waiting" by John M Ford - a story set in an alternate Renaissance history where magic does work; one of the Classic Fantasy reprints, this is a great read. Get this if you can (and proof that good fantasy stories can be one volume long!)
As for stuff I'd put on classic or must-read lists, I generally go by authors:
- Tolkien (of course:))
- Patrick O'Brian - Aubrey/Maturin, also the Golden Ocean and The Unknown Shore
- Iain (M) Banks - His fiction is good, his SF is superb
- Terry Pratchett - Best satirist currently writing (in any genre)
- George RR Martin - Game of Thrones, etc
- Peter F Hamilton - Greg Mandel trilogy, Night's Dawn Trilogy, etc
- David Weber - Honor Harrington series
- Lois McMaster Bujold - the Vorkorsigan saga, particularly the earlier books
- Arthur C Clark - Childhood's End, The City and the Stars, 2001
- Issac Asimov - Foundation trilogy, Robot trilogy, the short stories
- Frank Herbert - Dune, Dune Messiah
- Guy Gavriel Kay - Any and all
I could probably add a dozen others to the list if I put another five minute's thought into it...:)