This is a list that I produced when I was 19 years old of some of my favorite books. It is horribly out of date.
Robert A. Heinlein:
Stranger in a Strange Land — Everyone should read this one
The Moon Is a Harsh Mistress — Revolution made fun.
Starship Troopers — A fun war book and a different slant on politics.
Citizen of the Galaxy — One of the best Heinlein juveniles. This book really has a soul.
Friday — It's fun. It's got love, and violence, and politics, and superhumans, and it alwats keeps moving.
Job: A Comedy of Justice — Turns religion on it's head.
Time Enough for Love — It's a very very long book. It's really just a set of intertwined stories about one man and his life, all variation on the theme of love. It's got some realy good stuff in it, and don't feel bad about skipping parts of it.
Glory Road — A fun fantasy-adventure story that ends with
an morose overdose of reality.
Ringworld — It's worth reading for the concept alone.
The Ringworld Engineers — The sequel: almost as good.
Neutron Star (a collection of short stories) — Study your mechanics, then try and figure out the first story before the hero does.
The Mote in God's Eye (with Jerry Pournelle) — Heinlein called it "possibly the finest science fiction novel I have ever read." If sci-fi isn't your thing, this is the only Niven you have to read.
The Gripping Hand — The sequel.
Peter F. Hamilton's Night's Dawn Trilogy — possibly the best sci-fi of the 1990's.
The Reality Dysfunction: Emergence
The Reality Dysfunction: Expansion
The Neutronium Alchemist: Consolidation
The Neutronium Alchemist: Conflict
The Naked God
Dune — Worth reading.
Robert Jordan's Wheel of Time:
The Eye of the World, The Great Hunt, The Dragon Reborn, The Shadow Rising, The Fires of Heaven, The Lord of Chaos, A Crown of Swords, and The Path of Daggers - A damn good series, but it seems unlikely that Jordan would be able to finish it in his lifetime.
Old-school Pulp Sci-Fi:
Homer's Iliad — E. V. Reiu — my favorite translation of my favorite
classic. It's a prose tranlation. Verse translations loose something in the change. They sound fake.
Alfred, Lord Tennyson: Idylls of the King
The Feynman Lectures On Physics (3 Volume Set) — Not exactly a textbook, but the best lecture notes I've ever encountered.
QED : The Strange Theory of Light and Matter — As a simple explanation of advanced wave mechanics for non-physicists, it's beautiful.
Halliday, Resnick, Walker: Fundamentals of Physics (Extended) — Good intro physics text.
Paul Allen Tipler: Elementary Modern Physics — Good intro modern physics text.
David J. Griffiths: Introduction to Quantum Mechanics — Good quantum text. Funny, too.
Horowitz and Hill: The Art of Electronics — Great if you do practical electronics, but I gave up on being an experimentalist a while back.