I would say that the best I have seen, or at least the ones that gave a more realistic vision of how things might be for individuals in post SHTF situations would be:
Postman
I Am Legend
Castaway
The Stand (minus the supernatural Religious stuff)
The Road Warrior movies were fun, but I'm not sure how realistic an image they painted... certainly aspects of them were quite believable in terms of how it might be, but overall I'm not really buying it.
Each of these made honest attempts to depict how it would be to try and survive post SHTF w/o the aid of society as we are used to it.
I would also add the TV show Jehrico (Sp?) and the S.M. Stirling book series Emberverse (which starts with Dies the Fire) although that series also has supernatural/religious elements that should be ignored for the purposes of this conversation.
Personally I didn't care for The Road, the writing style/narration of the story irritated me to no end. However, I think it did do a good job of depicting what survival post SHTF might look like.
