Facebook Pages: How can one earn money with a facebook page?

Facebook is not a secret money pile just waiting to be found, but it can be a reliable source of extra income with some work and a clever approach.
These are the way you can do:

    Get many likes, then use it for advertising.
    Sell stuff to your friends.
    Sell stuff in selling/buying related groups.
or 
you have to do it start a blog and integrate it will google adsense and then share the topics on facebook. This way facebook will send traffic to your blog pages where your ads are already there and you will end up making money. Keep in mind that the quality of your contents should be very good and don't spam at all.