I have developed my own using enterprise value divided by...

I have developed my own using enterprise value divided by AISC-adjusted annual production. You can find a report I wrote under the Gold thread back in June for a more detailed discussion of the methodology using the ASX gold miners to illustrate. I think I titled it along the lines of Valuation Ranges of ASX gold miners.

Credit should be given to Don Durrett of GoldSilverData whose website inspired me to refine the method he used. Take a tour of his site if you have time!