Facebook app in MAMP

Hoi,
Not sure of the exact answer, actually, as Facebook sometimes has issues with port numbers. Please try the following settings though:
Site URL: http://localhost/
App Domains: <Leave Blank>

Let me know how that goes. It sounds wrong, but I think it should work for authentication on localhost with a port.

Thanks,
Alex

The logging in is the most important purpose for your application. The Like button error is likely the "Unreachable" message that is completely normal when running on Localhost. Facebook wants to 'see' your page to make sure it's not malware, porn, or other malicious content. Since it's on localhost, they can't do that and so therefore put up that message. When your site is live and some of the content is public, the message will go away.

Hope that helps,
Alex