Classic SCI FI Movies.

[Rommo]

No order

Riddick
Dune
Underworld (1 and 2)
Total Recall
Abyss
Mad Max

[MickyD]

So many to pick from but here's some that I really like. I don't think anybody's mentioned any of these so far:

Westworld
The Andromeda Strain
Planet of the Apes
Back to the Future
Time Machine (1960s version)