An interesting post calculating how much a Facebook Fan is worth. It's interesting because of the wide range of values attributed to a fan: $3 dollars up to $136.
Unfortunately, I'm not sure I buy the methodology behind the calculations. I just don't see how you can have a universal value attached to a Fan. It would vary so much depending on the brand, what it is selling, the level of engagement and the strategy behind the Facebook Page.
1 million impressions x two posts x 30 days = 60 million impressions
60M impressions / 1,000 x $5 CPM = $300,000;
$300,000 x 12 months = $3.6M;
$3.6M / 1M fans = $3.60