I'll add to the list as I remember them.
Fantasy:
The Elric Saga [http://www.multiverse.org/wiki/index.php?title=The_Elric_Saga_%28series%29] by Micheal Moorcock [http://en.wikipedia.org/wiki/Michael_Moorcock]
Wheel of Time [http://en.wikipedia.org/wiki/Wheel_of_Time] by Robert Jordan [http://en.wikipedia.org/wiki/Robert_Jordan] and, after his death, Brandon Sanderson [http://en.wikipedia.org/wiki/Brandon_Sanderson]
Science Fiction:
The Sprawl Trilogy [http://en.wikipedia.org/wiki/The_Sprawl_trilogy] by William Gibson [http://en.wikipedia.org/wiki/William_Gibson]
Anything by Philip K. Dick [http://en.wikipedia.org/wiki/Philip_Dick] (Special mentions to Do Androids Dream of Electric Sheep? [http://en.wikipedia.org/wiki/Do_Androids_Dream_of_Electric_Sheep%3F], A Scanner Darkly [http://en.wikipedia.org/wiki/A_Scanner_Darkly],
The Three Stigmata of Palmer Eldritch [http://en.wikipedia.org/wiki/The_Three_Stigmata_of_Palmer_Eldritch] and Ubik [http://en.wikipedia.org/wiki/Ubik])
Anything by Arthur C Clarke [http://en.wikipedia.org/wiki/Arthur_C_Clarke], starting with Childhood's End [http://en.wikipedia.org/wiki/Childhood%27s_End].
Anything by Isaac Asimov [http://en.wikipedia.org/wiki/Isaac_Asimov], starting with I, Robot [http://en.wikipedia.org/wiki/I,_Robot]
Bug Jack Barron [http://en.wikipedia.org/wiki/Bug_Jack_Barron] by Norman Spinrad [http://en.wikipedia.org/wiki/Norman_Spinrad]
Dune [http://en.wikipedia.org/wiki/Dune_%28novel%29] by Frank Herbert [http://en.wikipedia.org/wiki/Frank_Herbert]
I Have No Mouth and I Must Scream [http://en.wikipedia.org/wiki/I_Have_No_Mouth,_and_I_Must_Scream] by Harlan Ellison [http://en.wikipedia.org/wiki/Harlan_Ellison]
Farhenheit 451 [http://en.wikipedia.org/wiki/Farhenheit_451] by Ray Bradbury [http://en.wikipedia.org/wiki/Ray_Bradbury]
Crime:
Ian Rankin [http://en.wikipedia.org/wiki/Ian_Rankin]'s Inspector Rebus [http://en.wikipedia.org/wiki/Inspector_Rebus] series
James Ellroy [http://en.wikipedia.org/wiki/James_Ellroy]'s L.A. Quartet [http://en.wikipedia.org/wiki/L.A._Quartet] series
Anything by Jo Nesbo [http://en.wikipedia.org/wiki/Jo_Nesbo]
Other Must Reads:
1984 [http://en.wikipedia.org/wiki/Nineteen_Eighty-Four] and Animal Farm [http://en.wikipedia.org/wiki/Animal_farm] by George Orwell [http://en.wikipedia.org/wiki/George_Orwell]
Brave New World [http://en.wikipedia.org/wiki/Brave_New_World] by Aldous Huxley [http://en.wikipedia.org/wiki/Aldous_Huxley]
Of Mice and Men [http://en.wikipedia.org/wiki/Of_Mice_and_Men] by John Steinbeck [http://en.wikipedia.org/wiki/John_Steinbeck]
Lord of the Flies [http://en.wikipedia.org/wiki/Lord_of_the_Flies] by William Golding [http://en.wikipedia.org/wiki/William_Golding]
Things Fall Apart [http://en.wikipedia.org/wiki/Things_Fall_Apart] by Chinua Achebe [http://en.wikipedia.org/wiki/Chinua_Achebe]
Heart of Darkness [http://en.wikipedia.org/wiki/Heart_of_Darkness] by Joseph Conrad [http://en.wikipedia.org/wiki/Joseph_Conrad]
Anything by Jules Verne [http://en.wikipedia.org/wiki/Jules_Verne], my personal favourite being The Survivors of the Jonathan [http://en.wikipedia.org/wiki/Survivors_of_the_Jonathan]