What is the average economic value of a human life? What is the economic value of a human life?

If there are multiple methods to use in calculating, what are they, which method is preferred, and why?

Considerations/sub-questions on methods

A. Is the calculation purely based on output value (i.e. wages, goods produced, etc.), or are there intangibles that must be included (value of innovations that cause progress for society, NPV of progeny, etc.)?

B. As a result of #1, are there things which reduce economic value in one's life?  For example, when one has gone on unemployment, is one's net economic value negative for that period of time?

C.  Is the economic value of life dependent on one's country/state/locale or the sector one performs in?  For example, is it correct to say the economic value of a life is different in the US than in South Africa (due to average output in real terms?
It depends on the context, of course, but most often in policy analysis "the value of a life" has nothing (directly) to do with output, etc, but instead means the maximum amount that people would want the government to spend in order to save a randomly chosen life.  

So in a country of 300,000,000, the question is:  What, to you, is the monetary equivalent of a 1/300,000,000 chance of death?  Because 1/300,000,000 is a very small number, we don't have to worry terribly much about willingness-to-pay versus willingness-to-accept.  (Theory tells us that for small changes, the two willingnesses are effectively equal.)

Returning to the question:  How much would you be willing to pay to avoid a 1/300,000,000 chance of death?  Now multiply that value by 300,000,000.  That's the value of one life, and arguably the amount we'd want our government to spend to preserve a randomly chosen life.  

Obviously there are problems with heterogeneity (you and I might not answer the question identically).  But as a general rough rule, the estimates tend to come in somewhere under $10 million.