I set up a Facebook fan page a while ago. Now, I've put up a FaceBook Fan Box here at JoomlaBlogger.
This box displays fans of my Facebook page directly in Joomla. You can find the module in the right sidebar.
To put a box like this in your own site you have a few options.
When I first installed a Facebook module on my site, I had some trouble with it. I've now found another module which seems to work better.