Good thread, I have picked up a few recommendations to check out.

My suggestions:-
Dark Star - John Carpenters low budget first film
The Thing from Another World
The Thing (Inspired by The Thing from Another World)
Final Fantasy
T H X 1138 - George Lucas first film.
Babylon 5 - TV series
Dune
The Iron Giant
Pitch Black
Farscape - TV Series
Reign of Fire
War Of The Worlds (Original)
The Blob (Steve McQueen)
Super Troopers
Cloverfield
Killer Klowns From Outer Space
Zathura
Sharkboy & Lavagirl
Supernova