Great article last week in AdWeek.  The supposed media value of a fanbook fan is $3.60 per year.  In other words, based on the amount of exposure/word of mouth a single fan generates for your brand, if you have 5,000 fans, you would have to spend $18,000 per year in traditional media to generate the same amount of awareness.

For the particulars, read the article…it’s a good one