The weeping woman, the cough. Damn I am so tempted to play it again (does it make me a heartless psycho?), but I am at work :(
This is a great example of how some well though out details can play a massive role. Would the game be the same without the soundtrack, with the sounds of crying and coughing? It still would be a good game but not THAT good.
Don't forget the soundtrack! It added a lot to the game atmosphere :)