This small script for Facebook tabs initializes FB Connect API and set's it's size acording to the iframe's width and height.

FB-resize-tab

$.ajaxSetup({ cache: true });
$.getScript('//connect.facebook.net/es_LA/all.js', function(){
    FB.init({
      appId: 'appid',
    });                                     
    increaseIframeSize(w,h);        
});    

function increaseIframeSize(w,h){           
    var obj =   new Object;           
    obj.width=w;           
    obj.height=h;           
    FB.Canvas.setSize(obj);        
}