Facebook Crossdomain XML Policy if you developing Flash AS3 content for Facebook like showing Ablums you have to add following poilcy at the start of your Flash AS3

Security.loadPolicyFile("http://graph.facebook.com/crossdomain.xml");
Security.loadPolicyFile("https://graph.facebook.com/crossdomain.xml");
Security.loadPolicyFile("http://profile.ak.fbcdn.net/crossdomain.xml");
Security.loadPolicyFile("https://profile.ak.fbcdn.net/crossdomain.xml");
Security.loadPolicyFile('http://profile.cc.fbcdn.net/crossdomain.xml');
Security.loadPolicyFile('https://profile.cc.fbcdn.net/crossdomain.xml');
Security.loadPolicyFile('http://fbcdn-profile-a.akamaihd.net/crossdomain.xml');
Security.loadPolicyFile('https://fbcdn-profile-a.akamaihd.net/crossdomain.xml');
Security.loadPolicyFile('http://fbcdn-sphotos-a.akamaihd.net/crossdomain.xml');
Security.loadPolicyFile('https://fbcdn-sphotos-a.akamaihd.net/crossdomain.xml');
Security.allowDomain("*");
Security.allowInsecureDomain("*");

For share buttons Like and Simple APi calls a bit less works too. What i use at the moment for the MEtaplayer without photo content request.

// Facebook // https://s-static.ak.facebook.com/

Security.loadPolicyFile('https://api.facebook.com/crossdomain.xml');
Security.allowDomain('http://profile.ak.fbcdn.net');
Security.allowInsecureDomain('http://profile.ak.fbcdn.net');
Security.allowDomain('https://s-static.ak.facebook.com');

Yahoo Pipe Crossdomain

http://pipes.yahooapis.com/crossdomain.xml