Robert Heinlein
Double Star - Hardback, First Edition, First printing (1956), signed
Stranger in a Strange Land - HB, FE, FP (not signed).
Douglas Adams
Hitchhiker's Guide to the Galaxy. Complete set of the five books in the trilogy, HB, FE, FP
Frank Herbert
The Dosadi Experiment - HB, FE, FP, signed (my favorite SF book of all time)
David Brin
The Postman - HB, FE, FP (great book. The movie was a hatchet job, but the book is worth reading)
William Gibson
Neuromancer, Count Zero - HB, FE, FP
Anne Rice
Interview with A Vampire, Vampire Lestat - HB, FE, FP
and from a garage sale, a signed copy of "The Secret Agent" by Timothy Leary
