I've recently been given a brief based around the idea of waiting. My immediate thoughts on this turned to not necessarily the act of waiting, but more the moments building up to an event.
That powerless feeling you get when you know something is about to happen and you can't do anything about it, but also the 'release' moment. This could be a good thing, like a sense of relief or it could be that '.....shit' feeling when what you thought would go wrong has.
This clip from 'No Country for Old Men' illustrates this perfectly.
The tension comes from the moment, the long still shots of Chigurh's face, the silence of the scene building slowly with the back and forth dialogue gaining momentum until the gas attendant makes his choice.
In this similar moment from The Dark Knight, the tension builds from the ominous music and the swirling camera work causing a sense of claustrophic panic. All builds to a crescendo and then we get the 'release' feeling when The Batman turns up.