My favorites are probably 'A Boy And His Dog', 'Testament', 'Soylent Green' & 'The Omega Man'.
As for the newer movies, I've just seen '28 Weeks Later' and I basically think it's pretty good.
I'm very much looking forward to StarCraft 2. I just saw a 20 min clip of gameplay (Protoss against the Terran and Zerg) yesterday and I must say that it looks very impressive...