I have been really digging the iTunesU content recently and one lecture by Joel Peterson at Stanford GSB in particular.
Here is a link to the iTunes download:
Peterson is a longtime lecturer at GSB and has had a remarkable career in real estate and private equity. In this lecture he covers his way of thinking about Trust in great detail - the short version is that Trust is a bedrock requirement for business negotiation and that a person is worthy of trust when they have (1) Character (2) Competence and (3) Empowerment. That is a helpful set of criteria for assessing those your deal with and yourself .
Peterson highlights the importance of Trust by pointing out that all of our dealings - both business and personal - are "serial", as opposed to "episodic". In other words, our daily interactions are all part of a longer story - and how we behave in each of those interactions will determine the direction of the story.