Pinkros said:
Eulogy, Yojimbo and Secretary (last one only if you are mature enough to look through premises).
Secretary is beyond brilliant, I have to agree.
OP:
Interesting question. I'll NEVER suggest that someone "has" to see Pulp Fiction, tho. I'll prolly be crucified for this but...Tarantino is immensely overrated.
That being said, I'd agree with Blade Runner, The Godfather and A Clockwork Orange-tho even that movie was okay (before you start, I'm actually a HUGE Cult Movie fan, so it's not like it's a title I just don't like).
I'd go with:
The Shawshank Redemption
The Outlaw Josey Wales (or Once Upon A Time in the West)
Breatkfast At Tiffany's (for a "chick flick")
The Iron Giant (the ONLY "good" Vin Diesel movie)
Vertigo
Seven Samurai
Ghostbusters