my @urls = ('tp://www.foo.com/' , '://www.foo.com', 
            'http//:www.foo.com', 'www.foo.com',
            'xxx.tv', 'http//:xxx.tv', 'tp:xx.tv'); 

foreach (@urls)
{
   s/^(.*?)(\w+\.)/$2/;
   print "http://$_\n";
}

__END__
prints:
http://www.foo.com/
http://www.foo.com
http://www.foo.com
http://www.foo.com
http://xxx.tv
http://xxx.tv
http://xx.tv